Genesis 34:13

13.And the sons of Jacob answered. The commencement of their perfidious course is here related: for they, being outrageous rather than simply angry, wish to overthrow the whole city, and not being sufficiently strong to contend against so great a number of people, they contrive a new fraud, in order that they may suddenly rise upon the inhabitants weakened by wounds. Therefore, since the Shechemites had no strength to resist, it became a cruel butchery rather than a conquest, which increased the atrocity of wickedness in Jacob’s sons, who cared for nothing so that they might but gratify their rage. They allege in excuse, that, whereas they were separated from other nations, it was not lawful for them to give wives of their own family to the uncircumcised. Which indeed was true if they said it sincerely; but they falsely use the sacred name of God as a pretext; yea, their double profanation of that name proves them to be doubly sacrilegious; for they cared nothing about circumcision, but were intent on this one thing, how they might crush the miserable men in a state of weakness. Besides, they wickedly sever the sign from the truth which it represents; as if any one, by laying aside his uncircumcision, might suddenly pass over into the Church of God. And in this mode they pollute the spiritual symbol of life, by admitting foreigners, promiscuously and without discrimination, into its society. But since their pretense has some color of probability, we must observe what they say, that it would be disgraceful to them to give their sister to a man uncircumcised. This also is true, if they who used the words were sincere; for since they bore the mark of God in their flesh, it was wicked in them to contract marriages with unbelievers. So also, at the present time, our baptism separates us from the profane, so that whoever mixes himself with them, fixes a mark of infamy upon himself.