15 He who hath called you is holy He reasons from the end for which we are called. God sets us apart as a peculiar people for himself; then we ought to be free from all pollutions. And he quotes a sentence which had been often repeated by Moses. For as the people of Israel were on every side surrounded 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, “Ye have to do with me, ye are mine; then abstain from the pollutions of the Gentiles.” We are too ready to look to men, so as to follow their common way of living. Thus it happens, that some lead others in troops to all kinds of evil, until the Lord by his calling separates them.
In bidding us to be holy like himself, the proportion is not that of equals; but we ought to advance in this direction as far as our condition will bear. And as even the most perfect are always very far from coming up to the mark, we ought daily to strive more and more. And we ought to remember that we are not only told what our duty is, but that God also adds, “I am he who sanctify you.”
It is added, In all manner of conversation, or, in your whole conduct. There is then no part of our life which is not to be redolent with this good odour of holiness. For we see that in the smallest things and almost insignificant, the Lord accustomed his people to the practice of holiness, in order that they might exercise a more diligent care as to themselves.