By which also ye are saved,.... It was the means of their salvation, and had been made the power of God unto salvation to them. Salvation is inseparably connected with true faith in Christ as a Saviour, and with a hearty belief of his resurrection from the dead, which is the earnest and pledge of the resurrection of the saints; and because of the certainty of it in the promise of God, through the obedience and death of Christ, and in the faith and hope of believers, which are sure and certain things, they are said to be saved already.
To which the apostle puts in the following provisos and exceptions; the one is,if ye keep in memory what I preached unto you; or rather, "if ye hold fast, or retain"; that is, by faith, the doctrine preached to you, and received by you, particularly the doctrine of the resurrection of the dead; for the salvation that is connected with it does not depend upon the strength of the memory, but upon the truth and steadfastness of faith: it is the man that perseveres in the faith and doctrine of Christ that shall be saved; and everyone that has truly believed in Christ, and cordially embraced his Gospel, shall hold on, and out to the end; though the faith of nominal believers may be overthrown by such men, as Hymenaeus and Philetus, who asserted, that the resurrection was past already; but so shall not the faith of real believers, because the foundation on which they are built stands sure, and the Lord has perfect knowledge of them, and will keep and save them.