Christian princes (e.g.) sometimes marry Christian princesses from other Christian nations.
Intermarriage between a Catholic and a heretic (e.g.) is the New Testament's forbidden intermarriage.

You mean Vatican II dialogues?
Interracial children wouldn't be a problem if they don't bring their diverse manners and cultures into one house.
Our inheritance in this New Testament is not portions of lands but we are one, if only we drop our various traditions and really become one in Christ, following the Apostolic tradition.
Christ has come, and we are no longer looking for his coming from one particular tribe.
"...following the Apostolic tradition."