John Calvin Commentary 1 Peter 1:8

"whom not having seen ye love; on whom, though now ye see him not, yet believing, ye rejoice greatly with joy unspeakable and full of glory:" — 1 Peter 1:8 (ASV)

Whom having not seen, or, Whom though you have not seen. He lays down two things: that they loved Christ whom they had not seen, and that they believed in him whom they did not then behold. But the first arises from the second, for the cause of love is faith. This is not only because the knowledge of those blessings which Christ bestows on us moves us to love him, but also because he offers us perfect happiness and thus draws us up to himself.

He then commends the Jews because they believed in Christ whom they did not see, so that they might know that the nature of faith is to rest content in those blessings which are hidden from our eyes. They had indeed given some proof of this very thing, though in praising them, he is also guiding them in what they should do.

The first clause in order is that faith is not to be measured by sight. For when the life of Christians is apparently miserable, they would instantly fail if their happiness were not dependent on hope.

Faith, indeed, also has its eyes, but they are such as penetrate into the invisible kingdom of God and are content with the mirror of the Word; for it is the demonstration of invisible things, as it is said in Hebrews 11:1. Therefore, that saying of Paul is true:

we are absent from the Lord while we are in the flesh;
for we walk by faith and not by sight.
(2 Corinthians 5:6–7).

The second clause is that faith is not a cold notion, but that it kindles love for Christ in our hearts. For faith does not (as the sophists prattle) grasp God in a confused and implicit manner (for this would be to wander through devious paths), but it has Christ as its object.

Moreover, it does not grasp the mere name of Christ, or his bare essence, but considers what he is to us and what blessings he brings. For it is inevitable that a person's affections should be led to where their happiness lies, according to that saying:

Where your treasure is, there is also your heart (Matthew 6:21).

You rejoice, or, You exult. He again refers to the fruit of faith which he had mentioned, and not without reason; for it is an incomparable benefit that consciences are not only at peace before God, but confidently exult in the hope of eternal life. And he calls it joy unspeakable, or unutterable, because the peace of God exceeds all comprehension.

What is added, full of glory, or glorified, admits of two explanations. It means either what is magnificent and glorious, or what is contrary to that which is empty and fading, of which people will soon be ashamed. Thus, “glorified” means what is solid and permanent, beyond the danger of being brought to nothing.

Those who are not elevated by this joy above the heavens, so that being content with Christ alone, they despise the world, boast in vain that they have faith.