Psl 11:3- If the foundation be destroyed, what can the righteous do?
2Cor6:14 made it clear that we shouldn't be unequally yoked together with unbelievers, the undoing of Samson started when he began to mess around with strange women. As a believer, you're not permitted to marry an unbeliever- it is a standing order.
If you marry an unbeliever, you stand the risk of loosing heaven and raising spiritually imbalanced children. You may have seen couples of different faith professing to be living happily but I can tell you that they won't tell you their secret frustrations esp the woman.
If you're yet to marry and you're engaged to an unbeliever, don't try to convert him/her, you're not a converter, BREAK THAT RELATIONSHIP NOW. If you try to convert him/her, he may pretend because he wants to get you but when you eventually say 'I do', there's no going back.
If you're married to an unbeliever, you can only cry for mercy and practice 1pet3:1-2.
1- I break every unholy alliance that may lead to marriage In Jesus Name.
2- father, have mercy on my faulty marital foundation in Jesus Name.