John Calvin Commentary 1 Peter 1:15

"but like as he who called you is holy, be ye yourselves also holy in all manner of living;" — 1 Peter 1:15 (ASV)

He who has called you is holy. He reasons from the purpose for which we are called. God sets us apart as a peculiar people for Himself; therefore, we ought to be free from all pollutions.

He quotes a sentence often repeated by Moses. For as the people of Israel were surrounded on every side by heathens, from whom they might have easily adopted the worst examples and innumerable corruptions, the Lord frequently recalled them to Himself, as though He had said, “You have to do with Me; you are Mine. Therefore, abstain from the pollutions of the Gentiles.”

We are too ready to look to other people, so as to follow their common way of living. Thus it happens that some lead others in droves to all kinds of evil, until the Lord by His calling separates them.

In commanding us to be holy like Himself, the standard is not one of equals; rather, we ought to advance in this direction as far as our condition allows. And since even the most perfect are always very far from reaching this standard, we ought to strive daily more and more. We should also remember that we are not only told what our duty is, but that God also adds, “I am He who sanctifies you.”

It is added, In all manner of conversation, or, in your whole conduct. Therefore, every part of our life is to be redolent with this good odor of holiness. For we see that in the smallest and almost insignificant things, the Lord accustomed His people to the practice of holiness, so that they might exercise more diligent care over themselves.