Tertullian

“ Let us now recount the other dangers or wounds (as I have said) to faith, foreseen by the apostle; most grievous not to the flesh merely, but likewise to the spirit too. For who would doubt that faith undergoes a daily process of obliteration by unbelieving intercourse? “Evil confabulations corrupt good morals;” [9] how much more fellowship of life, and indivisible intimacy! Any and every believing woman must of necessity obey God. And how can she serve two lords [10] —the Lord, and her husband—a Gentile to boot? ”

“ If these things are so, it is certain that believers contracting marriages with Gentiles are guilty of fornication, [1] and are to be excluded from all communication with the brotherhood, in accordance with the letter of the apostle, who says that “with persons of that kind there is to be no taking of food even.” ”