6. Believers are called the sons of God, by a special adoption; which is farther to be considered, as being the subject-matter of this answer. Adoption is a word taken from the civil law; and it was much in use among the Romans, in the apostles time, in which it was a custom for persons, who had no children of their own, and were possessed of an estate, to prevent its being divided or descending to strangers, to make choice of such who were agreeable to them, and beloved by them, whom they took into this political relation of children; obliging them to take their name upon them, and to pay respect to them, as though they were their natural parents; and engaging to deal with them as though they had been so; and accordingly to give them a right to their estates, as an inheritance. This new relation, founded in a mutual consent, is a bond of affection; and the privilege arising from thence is, that he who is, in this sense, a father, takes care of, and provides for the person whom he adopts, as though he were his son by nature; and therefore Civilians calls it an act of legitimation, imitating nature, or supplying the place of it: and this leads us to consider, II. The difference between adoption, as used by men, and as it is applied in this answer, to God’s taking persons into this relation, as his children. 1. When men adopt, or take persons into the relation of children, they do it because they are destitute of children of their own to possess their estates; and therefore they fix their love on strangers: but God was under no obligation to do this: for if he designed to manifest his glory to any creatures, the holy angels were subjects capable of receiving the displays thereof; and his own Son, who had all the perfections of the divine nature, was infinitely the object of his delight, and, in all respects, fitted to be as he is styled, _Heir of all things_, Heb. i. 2.