I will quote Robert M. M'Cheyen-
"IV. The blessedness of being a son of God: 'Behold what manner of love the Father hath bestowed upon us, that we should be called the sons of God!' Ah! there are many things to make it a blessedness beyond compare.
1. The first thing that makes it a blessedness is that we get the love of the Father. The moment you become a child, the Father loves you. This is shown in what Christ said to Mary: 'I ascend unto my Father and to your Father, to my God and your God.' Christ here intimated, that we have the same love that he had. We have not got so much of the love of the Father as Christ, because he has got an infinite capacity; but it is the same love. The sun shines as much upon the daisy as it does upon the sunflower is able to contain more. Christ plainly shows you that in the 17th chapter of John, where he prays that the same love may be in us that was in him. O how much better is it, then, to be under the love of God, than under the wrath of God!
2. Let me mention to you a second part of the blessedness we get. The Spirit of the Son dwells in us. You will see this in Galatians 4,6 'Because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father.' Brethren, when Christ comes, the first thing he does is to redeem you from under the curse of the law, and then he makes you a son. O it is sweet to have the smile of Christ! it is sweet to get the love of Christ; but I will tell you what is equally as sweet-that is to receive the Spirit of Christ. Has he given you the Spirit? He will do it if you are a son, that you may be made to cry, 'Abba, Father.'
3. Let me mention to you another part of the blessedness of being a son of God. You get the likeness of the Father. You know this is the case in an adopted family; an adopted child in the course of time gets the very features of the family. So you get the image of the Father, and you get the love of the Father. You are taught that in Matthew 5, where Christ says, in his Sermon on the Mount, 'Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully used you, and persecute you; that ye may be the children of your Father which is in heaven,' that ye may bear the image of the Father. Have you that mark of adoption? Are you turning like God?.
4. Let us mention another part of the blessedness. Some of you may be surprised at it. We get the chastisement of the Father. If we have no chastisement, then we are bastards, and not sons, for what son is he whom the Father chasteneth not. The world are allowed to get fat; but it is not so with those that follow God; if they wander, he puts up a hedge, and if they fall into it, he puts up a wall.
5. Let me mention the last part of the blessedness. We receive the inheritance as heirs. Paul says, 'If sons, then heirs.' Every child in a rich family gets something when the father dies; often he shares his fortune equally among them, and the adopted child is not forgot. If we are Christ's we get all things with him. If we are Christ's, we share the government of the world with him. If we are his, we shall share the crown with him. It is called the inheritance of the saints in light. I cannot tell the blessings of being an heir of God; but I know that it is better than being an heir of hell: 'He that overcometh shall inherit all things,' and that for eternity-it cannot fade away. O my brethren! will you still remain heirs of hell? If you come to Christ you will be made heirs of God. Whether is it better to get the pleasure of the world, and hell at the end, or to be made a child of God, and an heir of Christ? 'They shall hunger no more, neither thirst any more; neither shall the sun light on them, nor any heat. For the Lamb which is in the midst of the throne shall feed them, and shall lead them unto living fountains of water: and God shall wipe away all tears from their eyes,' Rev. 7.16,17. O that God would make you like Mary, to choose that good part that shall never be taken away from you! O that God would put life into the dead stones, and from these stones raise up children to Abraham! Amen." Robert Murray M'Cheyne "A Basket Of Fragments" pg. 42,43