Exod 12:48.   And when a stranger shall sojourn with thee, and will keep the passover to the LORD, let all his males be circumcised, and then let him come near and keep it; and he shall be as one that is born in the land: for no uncircumcised person shall eat thereof. Gen 34:14.   And they said unto them, We cannot do this thing, to give our sister to one that is uncircumcised; for that were a reproach unto us: 1 Cor 10:21.   Ye cannot drink the cup of the Lord, and the cup of devils: ye cannot be partakers of the Lord's table, and of the table of devils.