Commentary on 1 Peter 1:1:
To the elect, or the elected. It may be asked, how could this be found out, for the election of God is hid, and cannot be known without the special revelation of the Spirit; and as every one is made sure of his own election by the testimony of the Spirit, so he can know nothing certain of others.
To this I answer, that we are not curiously to inquire about the election of our brethren, but ought on the contrary to regard their calling, so that all who are admitted by faith into the church, are to be counted as the elect; for God thus separates them from the world, which is a sign of election.
It is no objection to say that many fall away, having nothing but the semblance; for it is the judgment of charity and not of faith, when we deem all those elect in whom appears the mark of God’s adoption. And that he does not fetch their election from the hidden counsel of God, but gathers it from the effect, is evident from the context; for afterwards he connects it with the sanctification of the Spirit As far then as they proved that they were regenerated by the Spirit of God, so far did he deem them to be the elect of God, for God does not sanctify any but those whom he has previously elected.
However, he at the same time reminds us whence that election flows, by which we are separated for salvation, that we may not perish with the world; for he says, according to the foreknowledge of God This is the fountain and the first cause: God knew before the world was created whom he had elected for salvation.
But we ought wisely to consider what this precognition or foreknowledge is. For the sophists, in order to obscure the grace of God, imagine that the merits of each are foreseen by God, and that thus the reprobate are distinguished from the elect, as every one proves himself worthy of this or that lot. But Scripture everywhere sets the counsel of God, on which is founded our salvation, in opposition to our merits.
Hence, when Peter calls them elect according to the precognition of God, he intimates that the cause of it depends on nothing else but on God alone, for he of his own free will has chosen us. Then the foreknowledge of God excludes every worthiness on the part of man. We have treated this subject more at large in the first chapter of the Epistle to the Ephesians, and in other places.
As however in our election he assigns the first place to the gratuitous favor of God, so again he would have us to know it by the effects, for there is nothing more dangerous or more preposterous than to overlook our calling and to seek for the certainty of our election in the hidden prescience of God, which is the deepest labyrinth.
Therefore to obviate this danger, Peter supplies the best correction; for though in the first place he would have us to consider the counsel of God, the cause of which is alone in himself; yet he invites us to notice the effect, by which he sets forth and bears witness to our election. That effect is the sanctification of the Spirit, even effectual calling, when faith is added to the outward preaching of the gospel, which faith is begotten by the inward operation of the Spirit.
Calvin, John. Commentaries on the Catholic Epistles: 1 Peter 1:1. Available at:http://www.ccel.org/ccel/calvin/calcom45.iv.ii.i.html. Internet; Accessed 3 April 2009.