13 And not only stocks and stones, but even Satan himself, the destroyer of souls, have some ere now chosen for a father; to whom the Lord said as a rebuke, You do the deeds of your father, that is of the devil, he being the father of men not by nature, but by fraud. For like as Paul by his godly teaching came to be called the father of the Corinthians, so the devil is called the father of those who of their own will consent unto him.
For we shall not tolerate those who give a wrong meaning to that saying, Hereby know we the children of God, and the children of the devil, as if there were by nature some men to be saved, and some to be lost. Whereas we come into such holy sonship not of necessity but by choice: nor was the traitor Judas by nature a son of the devil and of perdition; for certainly he would never have cast out devils at all in the name of Christ: for Satan casts not out Satan. Nor on the other hand would Paul have turned from persecuting to preaching. But the adoption is in our own power, as John says, But as many as received Him, to them gave He power to become the children of God, even to them that believe in His name. For not before their believing, but from their believing they were counted worthy to become of their own choice the children of God.
Source: Catechetical Lectures (New Advent)