There are various characters, relations, and offices, which Christ sustains in the covenant of grace; among which, that of a federal Head is one: Christ is often said to be the "Head of the Church"; not of any particular congregation of saints, in this or the other part of the world; but of the church of the firstborn, whose names are written in heaven, even of all the elect of God, that ever have been, are, or will be in the world, (Eph. 1:22, 23, 5:23; Col. 1:18) and he is a Head to them in different senses; he is that to them as a natural head is to a natural body, and the members of it; which is if the same nature with it, superior to it, communicates life, sense, and motion to it, as well as overlooks and protects it; such an Head of influence is Christ to the church, the source of life to it, from whom nourishment is derived, and all the supplies of grace, (Eph. 4:15, 16; Col. 2:19). He is an Head in a political sense, as a captain general is head of his army, and a king is head of his subjects, (Judg. 10:18, 11:11; Hosea 1:11) and in an economical sense, as the husband is the head of the wife, and a father the head of his children, and a master the head of his servants and of his whole family (Num. 1:4; Eph. 5:23, 24; Isa. 9:6; Matthew 23:10). The headship of Christ in these several senses, chiefly belongs to his Kingly office; but besides these, he is the representative head of his church, or of all the elect of God; they were all considered in him, and represented by him, when he covenanted with his Father for them; all that he engaged to do and suffer, was not only on their account, but in their name and stead; and all that he received, promises and blessings, were not only for them, but he received them as representing them. As Christ was given to be the covenant of the people, so to be an Head of them in it (Eph. 1:22). And thus,
1. Christ was considered in election; he was chosen as Head, and his people as members in him, and so they had union to him, and a representative being in him before the world began; they did not then personally exist, but Christ did, who represented them, and therefore were capable of being chosen in him, as they were (Eph. 1:4).
2. Such a relation Christ stood in to them in the covenant, that was made, not with him alone, but with all the elect of God, considered in him as their head and representative; hence we read of "the covenant that was confirmed before of God in Christ"; which was of God made sure and firm with his covenant people, in Christ, as their Head, before the foundation of the world; when as yet they had not an actual being, only a representative one in Christ, (Gal. 3:17) and hence the covenant was made sure to them in him, before the manifestation and application of it to Abraham, and his spiritual seed spoken of in the preceding verse; so that "the law, which was four hundred and thirty years after" that revelation and manifestation of the covenant to Abraham, "cannot disannul, that it should make the promise of none effect"; for what commences in time, can never make void what was confirmed in eternity.
3. The promises of grace and glory, made to the elect of God in covenant, were made to them, as considered in Christ, their head and representative; for whereas these promises were made before the world began, (Titus 1:2) they could not be made to them in their own persons, but as represented by Christ, and therefore were made to him their Head, and to them in him; and hence the promise of life is said to be "in" him, (2 Tim. 1:1) and indeed, all the promises are Yea and Amen "in him" (2 Cor. 1:20). The apostle having said, that "to Abraham and his seed were the promises made", observes, "he saith not" and "to seeds, as of many, but as of one, and to thy seed, which is Christ"; who is the head and representative of all his spiritual offspring, and in whom they are all collected and considered; all the promises made, manifested, and applied to Abraham, and his spiritual seed, were originally made to Christ, the everlasting Father of his spiritual offspring, the common Head and Parent of them (Gal. 3:16).
4. All the blessings of grace, and grants of them in the covenant of grace, given and made to the elect in it, were given and made to Christ first in their name, and as representing them, and to them in him, as considered in him, their head and representative; for when these grants were made, and blessings bestowed, they were not in actual being, only had a representative one in Christ their head; hence grace is said to be given them "in Christ Jesus", before the world began; and they to be blessed with all spiritual blessings in heavenly places "in Christ", as they were chosen in him before the formation of the world (2 Tim. 1:9; Eph. 1:3, 4).
5. Christ, in the everlasting covenant, engaged in the name of his people, to obey and suffer in their stead; and accordingly he did both in time, as their Head and Representative. He obeyed the law, and fulfilled all righteousness, not as a single individual of human nature, and for himself, but as the federal Head of his people, as representing them; "That so the righteousness of the law might be fulfilled in us", says the apostle, (Rom. 8:4) that is, in the elect of God, they being considered in Christ their Head, when he became the fulfilling End of the law for righteousness unto them; and so they were made, or accounted, the righteousness of God "in him" their Head, (Rom. 10:4; 2 Cor. 5:21) in like manner as he in their name engaged to suffer for them; so in time he suffered in their room and stead, as their head and representative; insomuch that they may be truly said to suffer with him; they were all gathered together, recollected in one Head, "in Christ", and sustained and represented by him when he hung upon the cross, and are said to be "crucified with" him (Eph. 1:10; Col. 2:12).
6. In consequence of Christ’s covenant engagements and performances, when he rose from the dead, he rose not as a private Person, but as a public Person, as the head and representative of all those for whom he obeyed and suffered; and therefore they are said to be quickened and raised together with him, as they were then also justified in him, when he himself, as their Head and Surety was (Eph. 2:5, 6; Col. 3:1; 1 Tim. 3:16). Yea, Christ is also gone to heaven, not only as the Forerunner of his people, but as their Head and Representative; he has taken possession of heaven in their name, appears in the presence of God for them, and represents them, as the high priest did the children of Israel, in the holy of holies; and hence they are said to be made to sit together in heavenly places "in Christ Jesus" (Eph. 2:6).
7. The federal headship of Christ, may be argued and concluded from Adam being a federal head and representative of all his natural offspring; in which he was "the figure of him that was to come", that is, Christ; for it was in that chiefly, if not solely, that he was a figure of Christ; at least, that is the chief, if not the only thing the apostle has in view, (Rom. 5:14) as appears by his running the parallel between them, as heads and representatives of their respective offspring: Adam, through his fall, conveying sin and death to all his natural descendants; and Christ, through the free gift of himself, communicating grace, righteousness, and life to all his spiritual seed, the elect, the children his Father gave him: and hence these two are spoken of as the first and last Adam, and the first and second man; as if they were the only two men in the world, being the representatives of each of their seeds, which are included in them (1 Cor. 15:45, 47).
Now, as Christ stands in the relation of an Head to the elect, he has all things delivered into his hands; in honour to him, and in love both to him and them, and for their good; God has given him to be "Head over all things" to the church, (Matthew 11:27; John 3:35; Eph. 1:22) all persons and things are under his command, and at his dispose, to subserve his interest as Head of the church; even angels and men, good and bad, and all things in heaven and in earth; all power therein to protect and defend his people, and to provide for them; all fulness of grace, and the blessings of it to supply them; the government of the church, and of the world, is on his shoulders, who represents them; and therefore their persons, grace, and glory, must be safe in him; the covenant, and all its blessings and promises, are sure in him, the Head and Representative of his people in it.