The following is from Thomas Watson’s The Lord’s Prayer, commentary on the Westminster Shorter Catechism available for purchase here. He has treated the subject so richly, there’s not much I could add!
I. What is meant by God’s name?
To hallow, is a communi separare, to set apart a thing from the common use, to some sacred end. As the vessels of the sanctuary were said to be hallowed, so, to hallow God’s name, is to set it apart from all abuses, and to use it holily and reverently. In particular, hallowing God’s name is to give him high honour and veneration, and render his name sacred. We can add nothing to his essential glory; but we are said to honour and sanctify his name when we lift him up in the world, and make him appear greater in the eyes of others. When a prince is crowned, there is something added really to his honour; but when we crown God with our triumphs and hallelujahs there is nothing added to his essential glory. He cannot be greater than he is, only we may make him appear greater in the eyes of others.
 When we profess his name. Our meeting in his holy assembly is an honour done to his name. This is good, but it is not enough. All that wear God’s livery by profession are not true servants; there are some professors against whom Christ will profess at the last day. ‘I will profess I never knew you.’ Matt 7: 23. Therefore, to go a little further:
 We hallow and sanctify God’s name when we have a high appreciation and esteem of him, and set him highest in our thoughts. The Hebrew word to honour, signifies to esteem precious: we conceive of God in our minds as the most super excellent and infinite good; we see in him a constellation of all beauties and delights; we adore him in his glorious attributes, which are the several beams by which his divine nature shines forth; we adore him in his works, which are bound up in three great volumes — creation, redemption, and providence. We hallow and sanctify his name when we lift him highest in our souls; we esteem him a supereminent and incomprehensible God.
 We hallow and sanctify his name when we trust in it. ‘We have trusted in his holy name.’ Psa 33: 21. No way can we bring more revenues of honour to God, or make his crown shine brighter, than by confiding in him. Abraham ‘was strong in faith, giving glory to God.’ Rom 4: 20. Here was hallowing God’s name. Unbelief stains God’s honour and eclipses his name. ‘He that believeth not God has made him a liar’ (1 John 5: 10); So faith glorifies and hallows his name. The believer trusts his best jewels in God’s hands. ‘Into thine hand I commit my spirit.’ Psa 31: 5. Faith in a Mediator does more honour, and sanctifies God’s name more, than martyrdom or the most sublime acts of obedience.
 We hallow and sanctify God’s name when we never make mention of it but with the highest reverence. His name is sacred, and it must not be spoken of but with veneration. When the Scripture speaks of God, it gives him his titles of honour. ‘Blessed be the most high God.’ Gen 14: 20. ‘Blessed be thy glorious name, which is exalted above all praise.’ Neh 9: 5. To speak vainly or slightly of God is profaning his name, and is taking his name in vain. By giving God his venerable titles, we hang his jewels on his crown.
 We hallow and sanctify God’s name when we love his name. ‘Let them that love thy name be joyful.’ Psa 5: 11. The love which honours God’s name must be special and discriminating love — the cream and flower of our love; such as we give to none besides; as the wife honours her husband by giving him such love as she gives to none else — a conjugal love. Thus we hallow God’s name by giving him such love as we give to none else — a love joined with worship. ‘He is thy Lord; and worship thou him.’ Psa 45: 2.
 We hallow and sanctify God’s name when we give him a holy and spiritual worship. (1) When we give him the same kind of worship that he has appointed. ‘I will be sanctified in them that come nigh me:’ that is, I will be sanctified with that very worship I have appointed. Lev 10: 3. It is the purity of worship that God loves better than the pomp. It dishonours his name to bring anything into his worship which he has not instituted; as if he were not wise enough to appoint the manner in which he will be served. Men prescribe to him and super add their inventions; which he looks upon as offering strange fire, and as a high provocation. (2) When we give to God the same heart devotion in worship that he has appointed. ‘Fervent in spirit; serving the Lord.’ Rom 12: 11. The word for fervent is a metaphor, which alludes to water that seethes and boils over; to signify that our affections should boil over in holy duties. To give God outside worship, and not the devotion of the heart, instead of hallowing and sanctifying him in an ordinance, is to abuse him; as if one calls for wine and you give him an empty glass. It is to deal with God as Prometheus did with Jupiter, who did eat the flesh and present Jupiter with nothing but bones covered over with skin. We hallow God’s name and sanctify him in an ordinance when we give him the vitals of religion, and a heart flaming with zeal.
 We hallow and sanctify God’s name when we hallow his day. ‘Hallow ye the sabbath day.’ Jer 17: 22. Our Christian Sabbath, which comes in the room of the Jews’ Sabbath, is called the Lord’s day. Rev 1: 10. It was anciently called dies lucis, a day of light, wherein Christ the Sun of Righteousness shines in an extraordinary manner. It is an honour done to God to hallow his Sabbath. (1) We must rest on this day from all secular works. ‘Bring in no burden on the sabbath day.’ Jer 17: 24. As when Joseph would speak with his brethren he thrust out the Egyptians; so when we would converse with God on this day, we must thrust out all earthly employments. Mary Magdalene refused to anoint Christ’s dead body on the sabbath day. Luke 23: 56. She had before prepared her ointment and spices, but came not to the sepulchre till the Sabbath was past; she rested on that day from civil work, even the commendable and glorious work of anointing Christ’s dead body. (2) We must in a solemn manner devote ourselves to God on this day; we must spend the whole day with God. Some will hear the word, but leave all their religion at church; they do nothing at home, they do not pray or repeat the word in their houses, and so rob God of a part of his day. It is lamentable to see how God’s day is profaned. Let no man think God’s name is hallowed while his Sabbath is broken.
 We hallow and sanctify God’s name when we ascribe the honour of all we do to him. ‘Give unto the Lord the glory due unto his name.’ Psa 96: 8. Herod, instead of hallowing God’s name, dishonoured it by assuming that praise to himself which was due to God only. Acts 12: 23. We ought to take the honour from ourselves and give it to God. ‘I laboured more abundantly than they all;’ one would think this had savoured of pride: but the apostle pulls the crown from his own head and sets it upon the head of free grace: ‘Yet not I, but the grace of God which was with me.’ 1 Cor 15: 10. If a Christian has any assistance in duty, or victory over temptation, he rears up a pillar and writes upon it, Hucusque adjuvavit Deus. ‘Hitherto the Lord has helped me.’ John the Baptist transferred all the honour from himself to Christ; he was content to be eclipsed that Christ might shine the more. ‘He that comes after me is preferred before me.’ John 1: 15. I am but the herald, the voice of one crying; he is the prince. I am but a lesser star; he is the sun. I baptise with water only; he with the Holy Ghost. This is hallowing God’s name, when we transfer all honour from ourselves to God. ‘Not unto us, O Lord, not unto us, but unto thy name give glory.’ Psa 115: 1. The king of Sweden wrote this motto on the battle at Leipsic, Ista a Domino facta sunt — the Lord has wrought this victory for us.
 We hallow and sanctify God’s name by obeying him. How does a son more honour his father than by obedience? ‘I delight to do thy will, O my God.’ Psa 40: 8. The wise men showed honour to Christ, not only by bowing the knee to him, but by presenting him with gold and myrrh. Matt 2: 11. We hallow God’s name, not only by lifting up our eyes and hands to heaven and bowing the knee in prayer, but by presenting him with golden obedience. As the factor trades for the merchant, so we trade for God and lay out our strength in his service. It was a saying of Dr Jewel, ‘I have spent and exhausted myself in the labours of my holy calling.’ ‘To obey is better than sacrifice.’ The cherubim representing the angels are set forth with their wings displayed, to show how ready they are to do service to God. To obey is angelic; to pretend honour to God’s name, and yet not obey, is but a devout compliment. Abraham honoured God by obedience; he was ready to sacrifice his son, though the son of his old age, and a son of the promise. ‘By myself have I sworn, saith the Lord, for because thou hast done this thing, and hast not withheld thy son, thine only son: that in blessing I will bless thee.’ Gen 22: 16, 17.
 We hallow and sanctify God’s name when we lift up his name in our praises. God is said to sanctify, and man is said to sanctify. God sanctifies us by giving us grace; and we sanctify him by giving him praise. What were our tongues given for but to be organs of God’s praise? ‘Let my mouth be filled with thy praise and with thy honour all the day.’ Psa 71: 8. ‘Blessing, and honour, and glory, and power, be unto him that sitteth upon the throne, and unto the Lamb for ever.’ Rev 5: 13. Thus God’s name is hallowed and sanctified in heaven; the angels and glorified saints are singing hallelujahs. Let us begin the work of heaven here. David sang forth God’s praises and doxologies in a most melodious manner, and was, therefore, called the sweet singer of Israel. 2 Samuel 23: 1. Praising God is hallowing his name; it spreads his renown; it displays the trophies of his excellency; it exalts him in the eyes of others. ‘Whose offereth praise glorifieth me.’ Psa 123. This is one of the highest and purest acts of religion. In prayer we act like men; in praise we act like angels. Praise is the music of heaven, and a work fit for a saint. ‘Let the saints be joyful: let the high praises of God be in their mouth.’ Psa 149: 5, 6. None but saints can in a right manner thus hallow God’s name by praising him. As everyone has not skill to play on the viol and organ, so every one cannot rightly sound forth God’s harmonious praises; only the saints can do it; they only can make their tongue and heart join in concert. ‘I will praise the Lord with my whole heart.’ Psa 111: 1. ‘He was extolled with my tongue.’ Psa 66: 17. Here was joining in concert. This hallowing God’s name by praise is very becoming a Christian. It is unbecoming to murmur, which is dishonouring God’s name; but it becomes the saints to be spiritual choristers, singing forth the honour of his name. It is called the ‘garment of praise.’ Isa 61: 3. How comely and handsome is this garment of praise for a saint to wear! ‘Praise is comely for the upright.’ Psa 33: 1. Especially is it a high degree of hallowing God’s name when we can speak well of him and bless him in an afflicted state. ‘The Lord has taken away; blessed be the name of the Lord.’ Job 1: 21. Many will bless God when he gives, but to bless him when he takes away, is in a high degree to honour him and hallow his name. Let us thus magnify God’s name. Has he not given us abundant matter for praising him? He has given us grace, a mercy spun and woven out of his bowels; and he intends to crown grace with glory. This should make us hallow his name by being trumpets for his praise.
 We hallow and sanctify God’s name when we sympathise with him; when we grieve when his name suffers. (1) We lay to heart his dishonour. How was Moses affected with God’s dishonour! He broke the tables. Exod 32: 19. We grieve to see God’s Sabbaths profaned, his worship adulterated, the wine of truth mingled with error. (2) We grieve when God’s church is brought low, because his name suffers. Nehemiah lays to heart the miseries of Sion; his complexion begins to alter, and he looks sad. ‘Why is thy countenance sad?’ Neh 2: 2. What! sad, when the king’s cup-bearer, and wine is so near! Oh! but it fared ill with the church of God, and religion seemed to lose ground, and God’s name suffered; therefore Nehemiah grows weary of the court; he leaves his wine and mingles his drink with weeping. Such holy sympathy and grieving when God’s name suffers, he esteems as honouring and sanctifying his name. Hezekiah grieved when the king of Assyria reproached the living God. He went to the temple, and spread the letter of blasphemy before the Lord. Isa 37: 17. He no doubt watered the letter with his tears; he seemed not to be so much troubled at the fear of losing his own life and kingdom, as that God should lose his glory.
 We hallow and sanctify God’s name when we give the same honour to God the Son that we give to God the Father. ‘That all men should honour the Son, even as they honour the Father.’ John 5: 23. The Socinians deny Christ’s divinity, saying that he is a mere man: which is to make him below the angels. The human nature, considered in itself, is below the angelic, and thus they reflect dishonour upon the Lord of glory. Psa 8: 5. We must give equal honour to the Son as to the Father; we must believe Christ’s deity; he is the picture of his Father’s glory. Heb 1: 3. If the Godhead be in Christ, he must needs be God; but the Godhead shines in him. ‘In him dwelleth all the fulness of the Godhead bodily;’ therefore, he is God. Col 2: 9. How could these divine titles be given to Christ as omnipotence, in Heb 1: 3; ubiquity, in Matt 28: 20; a power of sealing pardons in Matt 9: 6; co-equality with God the Father, both in power and dignity, in John 5: 21, 23, if he were not crowned with the Deity? When we believe Christ’s Godhead, and build our hope of salvation on the corner-stone of his merit; when we see neither the righteousness of the law, nor of angels, can justify, but flee to Christ’s blood as to the altar of refuge; this is honouring and sanctifying God’s name. God never thinks his name hallowed unless his Son be honoured.
 We hallow God’s name by standing up for his truths. Much of God’s glory lies in his truths. His truths are his oracles. He intrusts us with his truths as a treasure; we have not a richer jewel to intrust him with than our souls, nor has he a greater jewel to intrust us with than his truths. His truths set forth his glory. When we are zealous advocates for his truths, it is an honour done to his name. Athanasius was called the bulwark of truth; he stood up in the defence of God’s truths against the Asians, and so was a pillar in the temple of God. We had better have truth without peace, than peace without truth. It concerns the sons of Zion to stand up for the great doctrines of the gospel; as the doctrine of the Trinity, the hypostatical union, justification by faith, and the saints’ perseverance. We are bid to contend earnestly, to strive as in an agony for the faith, that is the doctrine of faith. Jude 3. This contending for the truth, brings great revenues to heaven’s exchequer; and hallows God’s name. Some can contend for ceremonies, but not for the truth. We should count him unwise that should contend for a box of counters more than for his box of title-deeds.
 We hallow and sanctify God’s name by making as many proselytes as we can to him; when, by all holy expedients, counsel, prayer, example, we endeavour the salvation of others. How did Monica, Augustine’s mother, labour for his conversion! She had sorer pangs in travail for his new birth than for his natural birth. It is hallowing God’s name when we diffuse the sweet savour of godliness, and propagate religion to others; when not only we ourselves honour God, but are instruments to make others honour him. Certainly when the heart is seasoned with grace, there will be an endeavour to season others. God’s glory is as dear to a saint as his own salvation; and that this glory may be promoted he endeavours the conversion of souls. Every convert is a new member added to Christ. Let us then hallow God’s name by labouring to advance piety in others; especially let us endeavour that those who are nearly related to us, or are under our roof, may honour God. ‘As for me and my house, we will serve the Lord.’ Josh 24: 15. Let us make our houses Bethels, places where God’s name is called upon. ‘Salute Nymphas, and the church that is in his house.’ Col 4: 15. Let the parent endeavour that his children may honour God, and the master that his servants may honour him. Read the Word, drop holy instruction, perfume your houses with prayer. The Jews had sacrifices in their families as well as in the tabernacle. Exod 12: 3. This is hallowing God’s name when we make proselytes to him, and endeavour that all under our charge should honour and sanctify his name.
 We hallow God’s name when we prefer the honour of his name before the dearest things. (1) When we prefer the honour of God’s name before our own credit. The saints of old have, for the honour of God, been willing to endure reproach. ‘For thy sake I have borne reproach.’ Psa 69: 7. David cared not what reproach he suffered, so God’s name might not suffer. The prophet Elijah was called in derision, the ‘hairy prophet;’ and the prophet Isaiah ‘the bearer of burdens;’ and the prophet Zephaniah, ‘the bitter prophet;’ but they wound these reproaches as a crown about their head. The honour of God’s name was dearer to them than their own honour. Moses esteemed the reproach of Christ greater riches than the treasures of Egypt. Heb 11: 26. The apostles went away rejoicing that they were counted worthy to suffer shame for the name of Christ! that they were graced so far as to be disgraced for the name of Christ. Acts 5: 41. We hallow God’s name when we are content to have our name eclipsed, that his name may shine the more. (2) When we prefer the honour of God’s name before our worldly profit and interest. ‘We have forsaken all, and followed thee.’ Matt 19: 27. When these two, God and estate, come in competition, we would rather let estate go than God’s love and favour. Thus that noble Marquis of Vice parted with a fair estate, using these words, ‘Let their money perish with them, that count all the gold and silver in the world worth one hour’s communion with Jesus Christ.’ (3) When we prefer the honour of God’s name before our own life. ‘For thy sake we are killed all the day long.’ Rom 8: 36. The honour done to God’s name is not by bringing the outward pomp and glory to him as we do to kings, but it comes in another way, and that is by the sufferings of his people. When the world sees how entirely his people love him, that they will die in his service, it exalts and honours his name. God’s crown flourishes in the ashes of his martyrs. Basil speaks of a virgin, condemned to the fire, who having her life and estate offered her, if she would bow to the idol, answered, Valeat vita, pereat pecunia: Let life and money go, welcome Christ. When God’s glory weighs heaviest in the balance, and we are willing to suffer the loss of all rather than God’s name should suffer, we do, in a high degree, hallow God’s name.
 We hallow and sanctify God’s name by a holy conversation. ‘Ye are a royal priesthood, a peculiar people; that ye should show forth the praises of him who has called you.’ 1 Pet 2: 9. As an unholy life dishonours God’s name, ‘The name of God is blasphemed among the Gentiles through you;’ Rom 2: 24, so by our holy and Bible conversation we honour God’s name. A holy life speaks louder than all the anthems and praises in the world. Though the main work of religion lies in the heart, yet when our light so shines, that others behold it, we glorify God. When our lives shine, his name shines in us. The Macedonians used one day in the year to wear the picture of Alexander set with pearl and costly jewels; so when we carry the picture of Christ about us in our holy example, we bring honour to God’s name.