A far as I’ve been able to determine from the press coverage, Callista and Newt are both practicing Catholics united in Catholic matrimony.
They lived in flagrant adultery “back when,” but apparently a serious and sincere process of repentance and confession; and the formal annulment of prior null unions has got them to a place of lawful honorable wedlock. They now live straight and in the Sacraments. I hope we’re all OK with that.
Tony and Cherie Blair could make a similar claim. He formally converted to his wife's faith after leaving the Prime Minister's office, and by all accounts attends Mass weekly with his wife and children and his marriage is valid and recognized by Catholic canon law, and Tony Blair says he's a proud and faithful practicing Catholic.
Interesting thing, though, "practicing Catholic" Tony Blair has not changed his support for abortion or gay marriage.