Seems to me Underwood doesn't have a very strong grasp of what God's Word means for humankind. God set the rules.
Another female singer who marries a non-U.S citizen and suddenly takes on the spouse’s liberal views (see Ditzy Chicks). Country music and the American public say, “Goodbye, Mrs. Fisher.”
Maybe she just pretended she was Christian at first because it helped make her famous in the first place.
But the Bible was written by men, small m, not God. I do not trust men. God speaks to our individual souls. We must trust God in our individual souls. Right or Wrong God trusts his children.