That all who partake of this salvation, must partake of it in him, by virtue of union with him: But of him are ye in Christ Jesus, &c. As the stock is stay, strength, and sap to the branches; so is Christ wisdom, righteousness, sanctification, and redemption, to them that are in him, or unto sinners united to him. The sap of the stock is not conveyed to branches that are not in it: neither is Christ wisdom, &c. to any but those that are in him. He is the Saviour of his body; and we must partake of his salvation as members of his body. In the old world when the deluge came on, some without the ark getting up on the tops of trees or mountains, might be safe for a while; but none but those who were in the ark were safe to the end; so men that are out of Christ may get common temporal favours from the Lord; but none but those in him receive that wisdom, &c. which is the great salvation. The lost world is the first Adam, and the natural branches of that stock. The saved world are such branches as are taken out of that dead and killing stock, and ingrafted into Christ the true vine.
This then is the grand device of salvation, that Christ shall be all to sinners, and that they must partake of all in him; which is quite opposite to our natural imaginations, and exalts the free grace of God, depressing nature. (1.) They do not help themselves, their help is in another: He is made wisdom, &c. (2.) They do not so much as help themselves to their helper; for it is of God, by the power of his grace, that they are brought to be in him. It is not the branch itself, but the husbandman that ingrafts it.
Boston, T. (1848). The Whole Works of Thomas Boston: An Illustration of the Doctrines of the Christian Religion, Part 2. (S. M‘Millan, Ed.) (Vol. 2, p. 9). Aberdeen: George and Robert King.