That's not the interpretation of all churches - that it is a sin. For catholics, they have to get a dispensation involving the non-catholic party to agree to allow the catholic party to practice the faith and allow any children to be raised catholic. This includes marriage to protestants. It's not considered a sin whether the person is a non-catholic christian or non-christian. And actually, in ultra orthodox Judaism, it is forbidden for one to marry non-Jewish and there has to be a conversion of the non-Jewish partner first. Obviously, there are problems that can arise and such a marriage has to be carefully considered regarding religious and cultural practices of the partners. But being unequally yoked does not necessarily denote union with an immoral, "godless" or a sinner.
Did I say that? You can be unequally yoked with a person who knows the Lord. He said be ye not unequally yoked with unbelievers not be ye not unequally yoked with the unsaved only. You can be a Christian and an unbeliever.
What the bible says and what people do are two totally different things. In the OT the Lord forbids the Jews from marrying" strange women" people who are not Jewish. Do Jews still do it? Yes. Does that make it right with God? Nope, He is God and He does not change. There is even an instance in the OT where the Lord demanded the divorce of many couples (with children also) for disobeying Him and marrying non Jews. He means what He says.
In the NT, Paul says that Christians can marry whomever they wanted as long as in the Lord (another Christian to whom they are equally yoked). Do Christians continue to do it? Yep. Does it make it right with God? Nope.
He says what He says to protect us and save us from misery and to keep us from ruining our lives, and our childrens and their childrens lives.
We have a very high rate of divorce among Christians in this country. Why? Because we refuse to obey God and choose to marry folks who we are unequally yoked with in direct disobedience to His Word and protection. He knows that it's too much to bear everyday if we're trying to grow in our Christian walk to be bound to someone who isn't striving and believing the same thing but nope, we are wiser than God and we can be the exception
. Yet we want to blame God when our marriages began to fail after we done prayed to the Lawd for help and He or she STILL won't do right
It doesn't make the spouse a bad person, it just means that they don't believe the same that you do, the way that you believe it.