The most important piece of advice is that saying he knows Christ doesn't mean he has a relationship with Him.
Marriage based on a common faith is for our benefit, blessing and protection. Make the decision to follow Him and allow Him to help you find the right mate for you.
According to the scriptures, relationships are very important, and faith does matter.
After all, faith lays the foundation for your world-views, and world-views will control how you see and respond to the world, and that includes relationships.
Does the Old Testament have anything to say about marriages among God’s people and unbelievers?
In other words: If you are a Christian, you have no business dating an unbeliever, or entering into a marriage with a non-Christian.The Bible (and Jewish tradition) did allow for marriage between a believer and outsider, but only if the outsider converted. Otherwise, they were (and still are) commanded not to marry non-Christians/unbelievers.It is important to keep in mind that when a believer marries a non-believer, it can lead the Christian astray.The Bible says Solomon was the wisest man who had lived at that time, yet even he got swept up into idolatry.The Bible has much more to say about this issue of Christians marrying non-Christians: To the rest I say this (I, not the Lord): If any brother has a wife who is not a believer and she is willing to live with him, he must not divorce her.If you are already married, then don’t dissolve the marriage if your spouse is not a Christian, so long as the spouse is content to live with you.