Adam Clarke on 1 Peter 1:15

But as he which hath called you - Heathenism scarcely produced a god whose example was not the most abominable; their greatest gods, especially, were paragons of impurity; none of their philosophers could propose the objects of their adoration as objects of imitation. Here Christianity has an infinite advantage over heathenism. God is holy, and he calls upon all who believe in him to imitate his holiness; and the reason why they should be holy is, that God who has called them is holy, 1Pet 1:15.