Over the past three years, we have received a couple of questions about the Scriptural basis for the Church's historic prohibition of marriages between believers and unbelievers.1
Christians have typically supported the position that believers and unbelievers should not be married specifically through the text of 2 Corinthians 6:14-18:
Do not be unequally yoked with unbelievers. For what partnership has righteousness with lawlessness? Or what fellowship has light with darkness? What accord has Christ with Belial? Or what portion does a believer share 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 make my dwelling among them and walk among them, and I will be their God, and they shall be my people. Therefore go out from their midst, and be separate from them, says the Lord, and touch no unclean thing; then I will welcome you, and I will be a father to you, and you shall be sons and daughters to me, says the Lord Almighty."
It is certainly true that the passage does not explicitly say the words, "do not marry unbelievers," but it is impossible to escape the relevance and application to the context of marriage. Marriage is certainly a type of yoke2 and Paul does specify that an unequal yoke is one defined as being between a believer and an unbeliever. He does not say that believers should have no contact with unbelievers (1 Corinthians 5:10), but he does prohibit being yoked together. I think this passage has applications beyond marriage3, but certainly includes that relationship as well.
Although the 2 Corinthians passage alone should give us clear insight into God's revealed will in this matter, I would also consider the context of the Old Testament. The Torah specifically commands against marrying those of another nation. Those commands were not given to promote the ethnic superiority of Israel, but rather to prevent against one being led astray from faith in the true God. For example, see Deuteronomy 7:3-4 "You shall not intermarry with [the nations]; you shall not give your daughters to their sons, nor shall you take their daughters for your sons. For they will turn your sons away from following Me to serve other gods; then the anger of the LORD will be kindled against you." God's prohibition is an example of His mercy toward His people to keep their hearts from being misled to idolatry.
In addition to the above, I would look at 1 Corinthians 7:39 which speaks of marriage for those who have been widowed The widow is free to remarry, but only "in the Lord." I see no reason why we should conclude that shared faith is an extra requirement only for those who are widowed. The context of the 1 Corinthians instruction is also helpful as it specifically commands believers who are married to unbelievers to remain married (vss. 12-16). Why would Paul explicitly point out that believers should not divorce their unbelieving spouse? If Paul had to command the believer to stay married to the unbeliever, it is clear some must have thought the two should never have been married in the first place. Paul's conclusion for the context of an existing marriage between believer and unbeliever is that the marriage should remain intact and that good can come from such. However, this statement about the possibility of good coming from the marriage should not be used as justification of pursuing marriage with an unbeliever. God can bring sanctification and redemption through any sin, but that does not mean that we sin all the more so that good may come (Romans 6:1-2: "What shall we say then? Are we to continue in sin that grace may abound? By no means! How can we who died to sin still live in it?").
Practically speaking, I would want to examine the motivations of a believer who was considering marriage to an unbeliever. Why would a believer want to marry an unbeliever?4 What do they have in common that is of much ultimate significance? Their hopes are different, their beliefs are different, their loves are different, their joys are different, their convictions are different, their sources of ultimate authority are different, their worldviews are different; "What fellowship does light have with darkness?" as Paul writes in the 2 Corinthians passage. At the center of the affections of the believer is Jesus Christ and everything that he or she truly desires is found in getting more of Him. If marriage is meant more for our holiness than our happiness (a line from the book Sacred Marriage), then we should not marry someone who merely fulfills the longings of the flesh, but who will complement our spiritual thirst for Christ.
1 It is important to note that we are dealing with the issue of pursuing marriage and not commenting on believers and unbelievers who are already married. The Scripture is clear that believers and unbelievers who are already married should remained married (1 Corinthians 7:12-16).
2 When Matthew and Mark write about man and woman "joined" together by God in marriage (Matthew 19:6; Mark 10:9), they use a Greek word with "yoke" as its root. This root is the same as the one used in the 2 Corinthians 6 passage. In other words, the verbs in Matthew 19, Mark 10, and 2 Corinthians 6 are all etymologically related. God has "yoked" man and woman together into a one flesh relationship.
3 For instance, this has application within sphere of the business world The important point to be remembered is not that the Scripture forbids relating to unbelievers, but rather being yoked with them.
4 The same point could be made in reference to dating. God's provision for humanity's loneliness is fulfilled through a variety of means including: the indwelling presence of the Spirit in the believer, the gift of marriage, and the community of believers called "the church.' He did not intend for our desires to be met through casual romantic relationships with no intention of pursuing marriage. If dating is for the purpose of pursuing marriage, and if marriage to an unbeliever is prohibited, then it is certainly foolish for a believer to consider a romantic relationship with someone who does not trust Christ.