John Calvin Commentary 1 Peter 1:4

"unto an inheritance incorruptible, and undefiled, and that fadeth not away, reserved in heaven for you," — 1 Peter 1:4 (ASV)

To an inheritance—the three words that follow are intended to amplify God’s grace, for Peter (as I have said before) had this object in view: to impress our minds thoroughly with its excellence. Moreover, I consider these two clauses, “to an inheritance incorruptible,” etc., and “to salvation ready to be revealed,” to be in apposition, the latter being explanatory of the former, for he expresses the same thing in two ways.

Every word that follows is weighty. The inheritance is said to be reserved, or preserved, so that we may know that it is beyond the reach of danger. For, if it were not in God’s hand, it might be exposed to endless dangers. If it were in this world, how could we regard it as safe amidst so many changes? So that he might then free us from every fear, he testifies that our salvation is placed in safety beyond the harms that Satan can do.

But as the certainty of salvation can bring us little comfort unless each one knows that it belongs to himself, Peter adds, for you. For consciences will calmly find rest here, that is, when the Lord cries to them from heaven, “Behold, your salvation is in my hand and is kept for you.” But as salvation is not indiscriminately for all, he calls our attention to faith, so that all who are endowed with faith might be distinguished from the rest, and that they might not doubt that they are the true and legitimate heirs of God. For, as faith penetrates into the heavens, so it also appropriates to us the blessings that are in heaven.