Ye may know this (your adoption by God) by the following marks.
Mark 1. The image ye bear. Children are like their father, and all God’s children father themselves. I allude to Judges 8:18. They each one resemble the children of a king. Look to thy own soul, and say as Christ of the tribute-money, ‘Whose image and superscription is this?’ The image of God may shine more brightly in one than another, in one person at one time more than another; but his image is on all his children, 2 Cor. 3:18. If thou bearest his image, thou wilt be like him.
In the head, for there will be spiritual and saving knowledge, Col. 3:10. He is ‘the Father of lights,’ and his children are ‘children of light,’ Eph. 5:8. Ye that are yet living in your natural darkness, with whom there has been no morning to put an end to the darkness of a natural state, are yet of the family of Satan; and particularly grossly ignorant ones are so, Isa. 27:11. For though some of God’s children may not be book-learned, they are all Spirit-learned, John 6:45. But if God has enlightened your darkness and ye are renewed in knowledge, it is a good sign if ye are let into the knowledge of God and spiritual things, by the working of the Spirit of the Lord on you.
It is true, there is a false light, and a vain knowledge of spiritual things, even in the devil’s family; but saving knowledge is, (1.) Solid and humbling, Job 42:5, 6; and the more a man has of it, he is the more vile in his own eyes: the other is airy and windy, 1 Cor. 8:1. Knowledge puffeth up, and makes a man think himself something, when he is nothing. (2.) Lively and sanctifying, John 13:17. When the Spirit came on the primitive Church, Acts 2:3 there appeared tongues like fire: so true knowledge has a heat with it, to burn up known sin, and to burn toward known duty. They know and desire to know, in order to practise. The other is a sort of wild fire, that has light with it, but no heat; meet enough to lead people to the pit, where there is a burning heat but no light, 1 Cor. 8:1. Unholy ministers and professors, that have knowledge, they are like gentlemen skilled in architecture; all the use they have for it, is to tell how a house should be built, and draw the draughts, but they never lay a stone. The child of God is like the mason that learns the trade, to the end he may work in it daily. The former may have more of the theory than the latter, and can talk more rationally about it; but they are not called masons: the latter have more of the practice, so the name is theirs. Even so in spirituals, men not enlightened in the knowledge of God, so as to practise it in works of holiness, are not called of God Christians. (3.) Lastly, Experimental and savoury, Phil. 3:9. The child of God feels the power of truth on his soul. He sees the glory of Christ and religion, and he loves them, and is touched with the overcoming beauty. He feels the ill of sin, and he is put in horror with the deformity of it, 1 Peter 2:3. The other is speculative, unfelt untried, 1 Cor. 13:1–3. They speak of religion as a parrot, without the sense or knowledge of the things themselves, as a man does of war that was never at a battle, or one of sweet spices that he never saw, 1 Tim. 1:7.
In heart. Children readily partake of the disposition of their parents; so that as they are like them in the face, they are like them in their manners too. The child of God gets a new heart, Ezek. 36:26. So righteousness and holiness are parts of the image of God, Eph. 4:24. Every child of God is in some measure like David, a man after God’s own heart. The heart that was bent to evil, gets a set to the right side; the heart that was enmity against God, is turned to him. So that the soul loves what God loves, hates what he hates, sorrows for what grieves his Spirit, rejoices in what is acceptable to him. These are the upright and pure in heart in a gospel sense, Matth. 5:8.
But some will say, Well, I keep always a good heart to God. Others, Alas! the heart is the worst bit in me, where I can see the least likeness to God. Ans. Many that are first shall be last, and the last shall be first. The heart is both the best and worst bit in man. The best, Prov. 4:23; the worst, Jer. 17:9. And therefore I conclude, that the former sort are none of the children of God, because they are blind, and mistake the worst part of them for the best, the chambers of imagery for the temple of God, Rev. 3:17. Prov. 30:12. The latter sort may be God’s children; for that which makes the heart to be both the best and worst part, is, that in every heart of God’s family on earth, there is a renewed part, the spirit; and an unrenewed part, the flesh, Gal. 5:17; the one the best part, the other the worst. So that this holds of the children of God; for the best part of an unrenewed man is his life, be it never so bad, his heart is always worse, as the fountain is worse than the stream, Mark 7:21. Now, the child of God, looking on the unrenewed part of the heart, sees the worst bit in him: but if he look to the renewed part, it is the best for all that, better than his life, Psal. 45:13; be it never so good, Matth. 26:41.
The heart of a child of God is a roomy house; and grace and corruption in that heart are like two flitters, one going out of the house, the other coming into it. The outgoing tenant is loath to leave the house, makes no speed to lift his plenishing, but as the incomer lifts it for him to make room for his own. So here lies the one’s furniture, there the other’s in and about the same house. Even so God’s good things that he has in a saint, and the devil’s evil things that he has in him, are both to be found in the house of the heart, and standing about the door in the life. In the heart of a child of God, upon the one hand lies God’s plenishing, faith, humility, meekness, &c. on the other, Satan’s, unbelief, pride, passion, &c.; with this difference, that the latter is nearest the door, and all lifted out of their place, which they sometimes stood in, when they had the house there alone.
But what the differencing mark here of a heart on which God’s likeness is, is, that the law of God is written on that heart, Heb. 8:10. This is the peculiar privilege of a child of God. And it speaks three things.
(1.) A heart-approbation of the law. The law of God is holy and pure, condemning all impurity wherever it is found. But a child of God heartily approves of it, even though it strike against his most beloved idols. He approves of it in his judgment, as Just and righteous; and not only so, but in his practical judgment, as good as well as just, Rom. 7:12; which evidences the natural enmity to be broken, and the heart new moulded, Rom. 8:7.
(2.) A heart-inclination to the holy law. There is a principle within the man lying the same way with the law, and bending towards what it directs to, and away from what it forbids, Rom. 7:22. And though there be a contrary principle to this, which thwarts and crosses it, yet the child of God takes part with the former against the latter, and is striving and longing to be rid of it, Rom. 7:24. This is the new set of the heart, given in the new birth, consisting not in bare wishes to be conformed to that law, but in a resolute bent of the heart for it, which will never leave its struggling, till it overcome at last. And,
(3.) An universality in both, Psal. 119:6. It is not some shreds and pieces of the law that the heart approves of and inclines to, but the whole law, in every part thereof to them known, ver. 128. The holy law in all the parts thereof is a copy of the holy divine nature, and it is transcribed into the heart of the child of God, in so far as there are gracious inclinations wrought in the soul answerable to the several points of the law, as the wax bears the impress of the seal, John 1:16. So that try the child of God in his weakest side, this approbation and inclination will be found, Psal. 18:23.
In their walk, Eph. 5:1. As children follow their father’s footsteps, the children of God follow their heavenly Father. We have had the way of our Father, God, chalked out to us in the way our Lord took, and we must prove our sonship by following his steps, 1 John 2:6. He walked in the way of humility, meekness, self-denial, and heavenly-mindedness; and if we be following his steps in sincerity, conscientiously aiming at these things, it is an evidence we are the children of God.
Particularly, the way of love to men was a notable road of his, which we must follow, Eph. 5:2. A spirit of bitterness, fieryness. and selfishness, whatever men profess, is a black mark, it is so very unlike Christ’s way. And although the loving and seeking the good of our friends is so very rare in the world, and people generally hesitate not to return evil for evil, nay, many times working mischief to them that never wronged them; yet the loving of our enemies, as Christ loved his, and doing them good as we have opportunity, is absolutely necessary to evidence us to be the children of God, Matth. 5:44, 45.
Mark 2. By your affections to the family of God. A child of God has child-like affections to the family of heaven. Nature teaches us a special affection to our relations; and the new nature and state teaches the same to the heavenly family, betwixt whom there is a spiritual bond. Try the pulse of your affections, thereby to see your state.
A child of God has a child-like love and affection to God as his Father, and to Christ as his Elder Brother. This is a sure mark, 1 John 4:19. They bear a superlative, transcendent love to God and Christ, loving him above all persons, and all things. He is dearer to them than lawful or unlawful enjoyments, Psalm 73:25. And this love will manifest itself.
(1.) In honouring him as a father, Mal. 1:6. A child of God has an honour for him, which the rest of the world have not. He sees a glory, loveliness, and majesty in him above all other, 1 Pet. 2:7 which produces a love mixed with reverence, that makes up the child-like disposition.—These are separated in others. The presumptuous hypocrite seems to have a love to him, but they want reverence, and their pretended familiarity breeds contempt. The unrenewed heart, under convictions of sin and duty, has a slavish fear of him, but no love to him. But the child of God has love mixed with reverence.
(2.) A conscientious obedience to his commands, 1 John 5:3. The father’s command is a sufficient bond of obedience on a kindly child; and so is God’s on those that are his.—It is lamentable to think of the horrid untenderness and woful latitude that many take to themselves, whose conscience can witness, that God’s command, though known, has not the weight of a feather on their consciences, in many things; especially where their own interest is concerned, or in things that are thought light of by the world. But a child of God has weighty thoughts of God’s authority, smiles, and frowns, and will rather venture the displeasing of any than his Father.
(3.) In submitting to his chastisements, Micah 7:9. ‘I bear the indignation of the Lord,’ says the prophet, ‘because I have sinned against him.’ It is the disposition of a child of God, to justify God under the rebukes of providence, to condemn himself, and turn to the hand that smiteth.
(4.) In his absence from them, and displeasure against them, it is the disposition of a child of God, (1.) To take his absence heavily; so the spouse is heart-sick when her beloved is gone, a thing that many are very little acquainted with, Cant. 5:8. (2.) To justify him in his withdrawings; the soul leaves its complaint on itself, Psal. 22:1, 3. (3.) To long for his return and countenance, with a holy impatience, as Sisera’s mother, Judges 5:28. ‘Why is his chariot so long in coming? why tarry the wheels of his chariot?’ Psal. 63:1. ‘O God, thou art my God, early will I seek thee: my soul thirsteth for thee, my flesh longeth for thee in a dry and thirsty land, where no water is.’ (4.) To take rest in nothing while he hides his face. Worldly comforts, yea, gospel-ordinances, are sapless without him. Still they say with Job, ‘O that I knew where I might find him!’ Job 23:3. Lastly, To use all endeavours to find him, as the spouse did, Cant. 5.
(5.) Lastly, In his presence with them, and the outlettings of himself to them. (1.) To be well content in the enjoyment of himself instead of all things, Psal. 4:6, 7. (2.) To be inflamed with love to him, Luke 24:32. (3.) To be desiring more and more of his presence, Cant. 8:6. (4.) To like well the full enjoyment in heaven, Phil. 1:23. (5.) To be loath to part, Cant. 3:5.
And to clear yet more this mark of love to God,
[1.] It is love to God for himself; not only for what he has to give us, as the hypocrite’s servile love is; but also for what he is in himself, Psal. 45:2. ‘Thou art fairer than the sons of men: grace is poured into thy lips: therefore God hath blessed thee for ever, Psal. 73:25. ‘Whom have I in heaven but thee? and there is none upon the earth that I desire besides thee.’ They love him in all his perfections, particularly for his holiness and spotless purity, Psal. 97:12. ‘Ye that love the Lord, hate evil.’
[2.] They love what is his for his sake. His stamp and image on any thing makes it lovely to them, Psal. 26:8. ‘Lord,’ says David, ‘I have loved the habitation of thy house, and the place where thine honour dwelleth.’ Hence they love his truths, ordinances, and people. Which brings to a second particular.
He has a love to the brethren of the family, 1 John 3:14. For clearing this mark, consider,
(1.) It is a love to them as such, for the image of God appearing in them. When we love the godly for their godliness, the saints for their sanctity, we love God in them, and so may conclude, ‘that every one that loveth him that begat, loveth him also that is begotten of him,’ 1 John 5:1. Hypocrites may love saints, because of natural relation to them, their obliging conversation, their being of their way or opinion, and the like: but happy those who love them for naked grace in them, that pick the pearl out of the dunghill of many unpleasing things about them, and kindly love them for that.
(2.) It is an universal love, to all the saints, Eph. 1:15. A child of God will love all who to his discerning bear God’s image: not only the saints in gay clothing, but going in rags; not only those that are of our way, but of whatever party they be, if they agree with him in bearing God’s image.
(3.) Lastly, The more grace any have, they will have the more of the love of the child of God. The more like our heavenly Father, the more we will love them, since that likeness is the cause of the love.
Mark  ult. By your spirit. A child of God has the spirit of the family of heaven; the Spirit of adoption, Rom. 8:15. Now, the Spirit of adoption is,
A Spirit of prayer, ib. This casts all prayerless persons that are come to years of discretion, as none of God’s children. As it also casts all those, who, though they have a gift of prayer, and use it too, yet are strangers to the spirit of prayer. Now, the spirit of prayer makes spiritual worship, John 4:24; that is, by the Spirit he is helped to praying affections, seeking the enjoyment of God himself in the duty, and has his love, faith, humility, dependence on the Lord’s word through Christ, his sense of wants, sincere desire of supply, &c. stirred up in him by the Spirit, Rom. 8:6.
A spirit of liberty, not of bondage, ib. The Spirit of adoption carries a man out from the influence of the covenant of works, so that he does not serve God as a slave, merely or mainly for fear of punishment, or hope of reward; but as a son does a father, out of love.
Lastly, A noble spirit, that raiseth a man’s thoughts, aims, and designs, beyond the little mean things of this world; making him resolute for the enjoyment of God at any rate, and the land that is afar off, Num. 14:24. Those that are of noble families scorn to pursue the mean designs of the inferior sort, having a spirit suitable to their quality.—None are of such a noble extract as the saints are, by their new state: and their spirit is in some measure agreeable thereto.
Thomas Boston. The Whole Works of Thomas Boston: An Illustration of the Doctrines of the Christian Religion, Part 1. (S. M‘Millan, Ed.) (Vol. 1, pp. 629–635). Aberdeen: George and Robert King, 1848.