Hebrews 2:11

For both he that sanctifieth: for shows the reason of the Son's incarnation, viz. the necessity of union in nature between the sanctifying Mediator and the sanctified sinner. The great gospel Minister was to bring many sons to glory by suffering, which he was not capable of, but by being united to one and the same nature with them to whom the penalty was due, and so he must be Head of them. This God-man is separating and consecrating of penitent believing sinners from the common mass to God, meriting by his death for them remission of their sins, and sanctifying their persons by his Spirit from their pollutions by them, 1 Corinthians 6:11 Titus 3:4 Hebrews 9:14, Hebrews 10:10,14. And they who are sanctified; penitent believing sinners, justified by his blood, and sanctified by his Spirit, Ephesians 5:25. Are all of one: this is an attribute of the unity of the principle of both these; such an one as is proper to man with himself, whom he sanctifieth, and not competent to angels; it must therefore be the principle of humanity. He took a human soul and body united to his person, and so became of one nature with us, \compare Hebrews 2:14\ of one human mass, alluding to the first-fruits offered at the Passover, or the loaves at Pentecost, whereby all the rest were sanctified: so Christ assumed the same human nature, that he might be the Head and leading Representative of a body of mankind, differenced from them by his being holy, and they sinful, and personally united to the Word. For which cause he is not ashamed to call them brethren; the unity of him and them in the human nature, is the cause why he calls them brethren, therefore they must be one: considering him in the holiness of his Deity, and them in the filthiness of sin, he might have been ashamed of such a brotherhood; but by his effectual word he adopted them into a state of childship and heirship to God with himself; and in the flesh to give them that glory, that they might be one with God, as he and the Father are one, 1 Thessalonians 17:22.