It has often been noted that for the Apostle Paul, practical sanctification begins with your mind.
Your life is renewed as your mind is renewed (see Rom 12:1-2; Eph 4:22-24).
The same principle is taught by Peter. Here is a relevant passage:
But as He who called you is holy, you also be holy in all your conduct, because it is written, “Be holy, for I am holy.”And if you call on the Father, who without partiality judges according to each one’s work, conduct yourselves throughout the time of your stay here in fear; knowing that you were not redeemed with corruptible things, like silver or gold, from your aimless conduct received by tradition from your fathers, but with the precious blood of Christ, as of a lamb without blemish and without spot. (1 Pet 1:15-19).
Christians have a call to holiness (let no one say that Free Grace promotes licentiousness!). In fact, Peter says a judgment is coming—a judgment of works (which non-Dispensational commentators say is a judgment of works for eternal salvation, but which we know to be the Judgment Seat of Christ). Therefore, his readers must “conduct” themselves with reverence (“in fear”).
However, notice that after reminding them of that bit of doctrine, Peter appeals to their knowledge of another doctrine: “knowing that you were not redeemed with corruptible things…but with the precious blood of Christ.”
If reverential fear is not enough of a motivation on their behavior, maybe gratitude for Christ’s death will motivate them to holiness.
Either way, Peter assumes that knowing that judgment is coming, and that Jesus redeemed them with His own life should affect how they behave—especially since they knew that He redeemed them precisely from “aimless conduct” to holiness.
As was the case for Paul, so it is for Peter: knowledge precedes behavior, especially holiness.