Iain Murray won the honor of having his essay on election first in a collection of essays on Puritans. In quoting Thomas Goodwin at length, he highlights the precious link between the doctrine of election and the gospel itself.
Election is in relation to Christ. Now this truth lay at the very heart of their doctrine of election and determined every other part of gospel truth. God, says the apostle Paul, “hath chosen us in Him [in Christ] before the foundation of the world” (Ephesians 1:4). “His first choice of us was a founding us on Christ,” comments Goodwin on this verse, “and in and together with choosing us, a setting us into him, so as then to be represented by him. So that now we are to run the same fortune, if I may so spek, with Christ himself for ever, our persons being made mystically one with his, and he a Common Person to us in election. Other men, as likewise the angels that fell, were ordained to be in themselves,—to stand or fall by themselves…But we were considered in Christ from the first, and therefore, though we fall, we shall rise again in him and by him for he is a Common Person for us, and to stand for us, and is for ever to look to us, to bring us to all that God ordained us unto and so this foundation remains sure. We are chosen in Christ, and therefore are in as sure a condition, as for final perishing, as Christ himself…Remember election is unto this great privilege, to be in Christ, and one with him (of all the highest, and fundamental to all other)” (Goodwin’s Works, 1:76–77, Nichols).
It is not until we understand this point that we will see why the Puritans regarded a denial of the doctrine of election as an overthrow of the whole nature of the gospel. The great glory of the New Covenant is that God should carry out both His part and ours, and He does this by committing the elect to the care of Christ, by whom they are given all saving graces. (Iain Murray, Puritan Papers, vol. 1, pp 8–9).