I'm not sure if I am understanding this question correctly. If the person is asking if religion had anything to do with their marriage, then the answer would be no. Catherine, when she married Henry's older brother Arthur, brought a rich dowry to England and Henry VII didn't want to let it go after Arthur's death. The only real way of keeping it was to have Henry marry his brother's widow.
If the question is about the bible passages involved, that would be Leviticus 18 and Deuteronomy 20. The first passage deals with incestual adultery since the brother would still be alive; the second involves laws inheritance. In Henry and Catherine's case, the Deuteronomy passage would have applied, though Henry claimed Leviticus when he wanted to divorce her. Further point There was no denominational reason for the marriage. It took place in 1509 - in other words, before the start of the Reformation. The whole of Western and Central Europe was Catholic at the time.