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.
Look at Solomon: the Bible says his wives turned him towards other false Gods and idols.
For it came to pass, when Solomon was old, that his wives turned away his heart after other gods: and his heart was not perfect with the LORD his God, as was the heart of David his father.
1 Kings 11:4 The scripture above should be a “wake-up call” to Christians who think they can marry someone and not be influenced by their beliefs or faith.
The Bible says Solomon was the wisest man who had lived at that time, yet even he got swept up into idolatry.
The Bible is clear that Christians should not have close friendships with non-Christians.
But what does the Bible teach about dating and marriage? Is it a sin for a Christian to date a non-Christian?
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.
So what does the Bible say about dating or marrying an unbeliever?
First, for a historical perspective, let’s look at the Old Testament for a moment.
Does the Old Testament have anything to say about marriages among God’s people and unbelievers?
Yes: “An alien living among you who wants to celebrate the LORD’s Passover must have all the males in his household circumcised; then he may take part like one born in the land. Exodus These scriptures tell us that quite clearly even in the Old Testament God is very protective and serious about His followers being involved with people who did not follow God.