Marriage is a God-ordained union of two different people that they may become as one. This has been from the beginning when God created marriage, and will always be so.
Genesis 2:24 tells us,
"Therefore a man shall leave his father and mother and be joined to his wife, and they shall become one flesh."
This is a truth that no man or woman can avoid. No matter who you marry, you will be joined to your spouse and you shall become one with your spouse.
For this reason, the Bible sternly warns every Christian believing in the Lord not to marry an unbeliever. 2 Corinthians 6:14 warns all believers,
"Do not be unequally yoked together with unbelievers. For what fellowship has righteousness with lawlessness? And what communion has light with darkness?"
This is not just for marriage. This warning is given to all Christians who are thinking of partnering with others in any pursuit, but it should be applied all the more to marriage, which is a lifelong pursuit and union from which no separation can ever be acceptable to the Lord:
"For the Lord God of Israel says that He hates divorce, for it covers one's garment with violence..." (Malachi 2:16)
Are you a Christian married to an unbeliever? Worry not, this article is not written to condemn you. Rather, it was written to help you see the goodness and the grace of God for you. Keep reading.
For believers who married non-believers
There are some Christians who married non-believers, ignoring 2 Corinthians 6:14 and the many warnings God gave in the Bible about marrying with people of different faiths, especially in the Old Testament.
The reason why God gave such warnings and commands is not because He's a killjoy, or not because He hates non-believers. Both are contrary to His nature: He wants us all to be full of His joy, and He loves non-believers too.
There is, however, a great danger when a believer marries an unbeliever: faith will be tested and challenged, even to the point where the believer might compromise. Deuteronomy 7:3-4 says of intermarriage:
"Nor shall you make marriages with them. You shall not give your daughter to their son, nor take their daughter for your son. For they will turn your sons away from following Me, to serve other gods; so the anger of the Lord will be aroused against you and destroy you suddenly." (emphasis mine)
Knowing this, here are a few things Christians married to non-Christians should always remember to think and do:
1) Repent of this disobedience
If you became Christian after marrying a non-Christian, then it's not wrong to have married that person. You can simply proceed to points 2 and 3.
If you were already Christian before marrying an unbeliever, and have been forewarned about such a marriage, you need to repent of it. Of course you don't seek to divorce or separate yourself from your spouse, but you must repent of such disobedience to God's Word.
2) Realize that your faith in God will be challenged
Having an unbelieving spouse will be challenging. 1 Corinthians 7:33 tells us that married people think about how to please their spouse. The issue of having different faiths adds more trouble to the already heavy burden of marriage.
Your spouse will compete with your devotion to God. While some unbelieving spouses will simply allow their believing spouses to go on and worship God, some won't. And this is where it gets difficult. Be prepared to face discouragement.
3) Realize that God wants you and your spouse, as well as your family, saved
Though it may be challenging to have an unbelieving spouse, it will be very encouraging to know that God loves your spouse and family too. In fact, He wants them saved (see 1 Timothy 2:4).
Be encouraged by this wonderful promise in the book of Acts:
"And [the keeper of the prison] brought [Paul and Silas] out and said, "Sirs, what must I do to be saved?" So they said, "Believe on the Lord Jesus Christ, and you will be saved, you and your household."" (Acts 16:30-31, emphasis mine)
God wants your family saved, including all unbelievers especially your spouse. Pray for your spouse. Pray for God's salvation to come into your home. Share the Gospel with them, and live a life that shows God's goodness to them.