I want to say this matter is covered in the Bible and I perceive it to be divided up into two issues:
If you're already married at the time you (the christian) become saved: (see bolded in the red below).
1 Corinthians 7
Marriage
12To the rest I say this (I, not the Lord): If any brother has a wife who is not a believer and she is willing to live with him, he must not divorce her. 13And if a woman has a husband who is not a believer and he is willing to live with her, she must not divorce him. 14For the unbelieving husband has been sanctified through his wife, and the unbelieving wife has been sanctified through her believing husband. Otherwise your children would be unclean, but as it is, they are holy.
15But if the unbeliever leaves, let him do so. A believing man or woman is not bound in such circumstances; God has called us to live in peace. 16How do you know, wife, whether you will save your husband? Or, how do you know, husband, whether you will save your wife?
17Nevertheless, each one should retain the place in life that the Lord assigned to him and to which God has called him. This is the rule I lay down in all the churches. 18Was a man already circumcised when he was called? He should not become uncircumcised. Was a man uncircumcised when he was called? He should not be circumcised. 19Circumcision is nothing and uncircumcision is nothing. Keeping God's commands is what counts. 20Each one should remain in the situation which he was in when God called him. 21Were you a slave when you were called? Don't let it trouble you—although if you can gain your freedom, do so. 22For he who was a slave when he was called by the Lord is the Lord's freedman; similarly, he who was a free man when he was called is Christ's slave. 23You were bought at a price; do not become slaves of men. 24Brothers, each man, as responsible to God, should remain in the situation God called him to.
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Then I believe there is the issue of being saved before you are married. If that's the case, I believe the Bible speaks against it.
2 Corinthians 6:14 - Do not be yoked together with unbelievers. For what do righteousness and wickedness have in common? Or what fellowship can light have with darkness?
2 Corinthians 6:15-17 - What harmony is there between Christ and Belial? What does a believer have in common with an unbeliever? What agreement is there between the temple of God and idols? For we are the temple of the living God. As God has said: "I will live with them and walk among them, and I will be their God, and they will be my people." Therefore come out from them and be separate, says the Lord. Touch no unclean thing, and I will receive you”
1 Corinthians 15:33 - Do not be misled. Bad company corrupts good character.
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I know these verses don't mention marriage specifically but it seems like they would apply.
To those who have interfaith marriages, I have a couple of questions.
If you were dating someone of a different faith and you are a Christian, what is your goal. Is it romancing them or winning their soul for Christ?
How do you have a spiritual relationship if you don't believe in the same things?
How do you focus on having a blessed and quality marriage if you disagree on the most important issue for Christians. The Savior.
Now, I want to say that 1 Corinthians 7 goes on to talk about.
Regardless of the aforementioned issues and questions, it seems that God would advise that a christian not marry a non-christian but that he hates divorce (Malachi 2:16, “I hate divorce says the Lord God.” )
so much that if you happened to be married to a christian at the time you are saved, he'd rather you stay in that marriage and live a life that would win your husband to Christ rather than just divorcing him.
Just my .02 cents.
And although we are under New Testament Law. There are many times in the Old Testament when God admonished folks for interfaith marriages because he didn't want them succumbing to the worship of idols.
A lot of people think that interracial dating is prohibited because one of the issues in the Bible can be confusing for some.
If you'll recall, the Old Testament law commanded the Israelites not to engage in interracial marriage in Deuteronomy 7:3-4. The reason for this is that the Israelites would be led astray from God if they intermarried with idol worshippers, pagans, or heathens. It wasn't about "race" per se. It was about the fact that the other "races" at that time were not worshipping God.
Just as the Israelites who were believers in God were commanded not to marry nonbelievers, Christians are commanded not to marry unbelievers. Exception, again, I believe is made for those who are already married at the time of being saved.