1 Peter 1:15

but like as he who called you is holy, be ye yourselves also holy in all manner of living;

Hunter properly discerned that the requirement here is about the same as that of Matthew 5:48, namely, perfection.[45] Isaiah referred to the Father as "the Holy One of Israel" (Isaiah 30:15); and the great premise here is that children of such a God must themselves be holy "in all manner of living." The writer of Hebrews likewise admonished to "Follow ... holiness, without which no man shall see the Lord" (Hebrews 12:14 KJV). The theologians may speak as long and as lustily as they like about being saved "through faith alone," but this and a thousand other New Testament passages teach otherwise. Nor is this to allege that man has the ability to achieve this apart from being "in Christ."