1st Corinthians 7:17

14 for the unbelieving husband hath been sanctified in the wife, and the unbelieving wife hath been sanctified in the husband; otherwise your children are unclean, but now they are holy.

15 And, if the unbelieving doth separate himself -- let him separate himself: the brother or the sister is not under servitude in such [cases], and in peace hath God called us;

16 for what, hast thou known, O wife, whether the husband thou shalt save? or what, hast thou known, O husband, whether the wife thou shalt save?

17 if not, as God did distribute to each, as the Lord hath called each -- so let him walk; and thus in all the assemblies do I direct:

18 being circumcised -- was any one called? let him not become uncircumcised; in uncircumcision was any one called? let him not be circumcised;

19 the circumcision is nothing, and the uncircumcision is nothing -- but a keeping of the commands of God.

20 Each in the calling in which he was called -- in this let him remain;