If you look at the passage in several translations you will see some differences in the way the committees handled Peter’s Greek, 1 Peter 1:13, 1 Peter 1:13 NIV, 1 Peter 1:13 NIV84, 1 Peter 1:13 ESV, 1 Peter 1:13 NET. When you see those differences it indicates that the original is difficult or else has some interesting nuances. In this instance the word that caught my attention is the word that is translated “mind.”
διανοία (dianoia). It has the sense of how we understand, process information, like our world view. What Peter seems to be saying here is that in light of the reality of the gospel which, in the immediate context, neither the prophets nor the angels understood, we are to soberly control the way we think in light of the overwhelming grace that God has afforded us in Christ.
Paul takes this same tack in 2 Corinthians 10:5, when he states that he is, “taking every thought captive to the obedience of Christ.” Again in Romans 12:2, Paul alludes to this same idea, our minds are to be transformed. As believers how we think, how we process information, how we consider options, how we react to that information is to be guided and conformed to the grace of Christ.