Forbidden by God

Marriage between believers and unbelievers is forbidden by God. This should be reason enough to not even consider the possibility of taking this step.

2 Corinthians 6:14-18 Do not be mismated with unbelievers. For what partnership have righteousness and iniquity? Or what fellowship has light with darkness? What accord has Christ with Belial? Or what has a believer in common with an unbeliever? What agreement has the temple of God with idols? For we are the temple of the living God; as God said, "I will live in them and move among them, and I will be their God, and they shall be my people. Therefore come out from them, and be separate from them, says the Lord, and touch nothing unclean; then I will welcome you, and I will be a father to you, and you shall be my sons and daughters, says the Lord Almighty."

"Never should God's people venture upon forbidden ground. Marriage between believers and unbelievers is forbidden by God. But too often the unconverted heart follows its own desires, and marriages unsanctioned by God are formed. Because of this many men and women are without hope and without God in the world. Their noble aspirations are dead; by a chain of circumstances they are held in Satan's net. Those who are ruled by passion and impulse will have a bitter harvest to reap in this life, and their course may result in the loss of their souls." --Ellen G. White, Adventist Home, p. 63