Believers and unbelievers should never be unequally yoked. 2 Corinthians 6:14-18 tells Christians this, but many times we disregard or violate these verses. King Solomon is a perfect example of what happens when you violate this verse. Nehemiah had to remind the returning children of Israel from captivity in Babylon concerning this.
(I have to confess I had to shoot this video quickly because I had many things to do after work, including dropping our kids off at a youth event and taking my wife to dinner. By the time I would get back home it would've been too late to shoot this video. I apologize if it is not clear or rushed.)