We must approach the subject of the unequally yoked marriage from two perspectives. First, we will deal with the Christian who is considering marrying an unbeliever. Second, we will discuss the Christian who is already married to an unbeliever.

What is an Unequally-Yoked Marriage?

In 2 Cor. 6:14 we are told not to be unequally yoked together with unbelievers. This verse is more clearly understood in light of Deut. 22:10 where it commands to not plow with an ox and a donkey yoked together. Why?

The ox and the donkey are two different kinds of animals.
Because of their different leg lengths, the ox and the donkey walk differently with their strides and paces.
The ox is much stronger than the donkey.
The ox and donkey think, act, and work differently.
The donkey eats a certain weed that makes the ox nauseous if it eats it.
The unequal yoke causes the animals to get wounds where the yoke rubs them wrongly.
The unequal yoke makes the furrow crooked rather than straight, causing the plowman to work extra hard to keep the plow and animals in line.
The apostle Paul uses this example to illustrate why a Christian should not be unequally yoked together with a non-Christian. Why?

The Christian and non-Christian are two different kinds of people, with two different fathers (John8:42,44)
They have two different walks, or lifestyles (Eph 2:1-2, 5:8).
The Christian is spiritually much stronger than the non-Christian.
They both think, act, and work differently.
What they both "feed on" makes the other nauseous.
They get wounded because they get rubbed the wrong way.
The spouses must work extra hard to keep the marriage in line.

When we are making decisions, God deals with us in two different ways. Before we decide, God deals with us in one way. After we decide, God deals with us in another way. If you are a Christian who wants to marry an unbeliever, you must first realize that the strongest yoke you can make on earth is the yoke of marriage. Once you tie the knot with the person, God will acknowledge it as so and will expect you to stay with him or her until death.
This is why God commands us not to be yoked with an unbeliever, but to marry only in the Lord (1Cor 7:39). It doesn't matter how cute he is, how popular or nice, or how great his personally is, there is a part in him that you can't see that will make your "plowing" in life very difficult. You will be amazed how his "cuteness" disappears when he starts yelling at you. His spirit inside is dead in sin, while yours is alive in Christ (Eph 2:1,5). This will influence nearly every decision that you will make, as well as the people you associate with. Because you have two completely different philosophies of life, you will probably argue more than if your were in a Christian marriage. Don't expect him to get excited about spiritual things and don't be surprised when he wants you to compromise your convictions. Christians who are married to unbelievers continually have problems in these areas. God wants a Christian to only marry another believer.

If you are already married to an unbeliever, you are probably wondering, "Am I out of God's will now that I am married to an unbeliever? Has God forsaken me?" The answer is clearly, "No!" It may seem contradictory to say it's wrong to marry an unbeliever, and then say you can be in God's will after you have married him.
But remember, God works with us in one way before we make a decision through pointing us down the right path. He works with us in a different way after we have made the decision through accepting our decision and working in it. This can be verified throughout Scripture, particularly in Romans 8:28. Isn't it great to know that we serve such a loving, all-knowing, gracious God that when we make a mistake, we are not doomed to live forever in condemnation! By dedicating our wrong decisions to God, He will accept us in our present situation and work our decisions into His will (Eph. 1:11). He will do the same with your unequally yoked marriage.
As a word of encouragement to Christians who have unbelieving spouses, some of the most loving and blessed Christian married couples that I know started out with both spouses as unbelievers in a totally non-Christian marriage. Along the way, one got saved and then the other, and they now have a beautiful Christian marriage. If you are a believer, at least you are now half way there! Your spouse might be fighting against God, but wouldn't it wonderful to see him saved so that God can do a miracle in your marriage too? Don't give up hope!
No doubt many of you who have unbelieving spouses have already gone through a lot of heartache. I'm sure you have even been persecuted by the one you are closest to. Here are some things that will help you when the going gets tough:

1. Realize that God knows about your situation.

It helps to know that God understands what you are going through. A sparrow can't fall to the ground without our Father knowing about it (Matt 10:29-31). God knew millions of years ago whom you would marry, and it didn't take Him by surprise. He desires to work in your marriage.
2.Don't divorce your unbelieving spouse
First Corinthians 7:12-16 tells the Christian not to divorce the unbelieving spouse. This is clear evidence that you can be in God's will while married to an unbeliever. Some of the Corinthian Christians thought that since they were married to unbelievers, then their marriages were polluted and rejected by God. Paul tells them in 1Cor 7:14 that their marriages had the opposite effect--that the unbelieving husband and any children were sanctified, that is set apart by God because of the Christian wife.
Although the believer is not to leave the unbeliever, if the unbeliever departs, then let him depart (v.15). You can't make the unbeliever accept Christ and if he chooses to leave, then you are not under bondage to him anymore because God has called you to peace (v.15).
3. Let God use you in your marriage
God wants to use you as an instrument to bring your family to Himself. One of the primary areas of evangelism and ministry should be the family. God used the Philippian jailer to win his household to Christ in Acts 16:25-34. First Peter 3:1-4 tells us that an unsaved husband can be won to the Lord through seeing his wife's godly behavior and attitudes. A submissive and godly attitude can open his heart to the Lord.
4. When your spouse causes trouble, realize where it is coming from.
We have a tendency to look at the person, rather than the spirit behind the person. We don't wrestle with flesh and blood, but with demon spirits (Eph 6:12). Once we realize that the real problem is Satan, we have a much easier time with the person that Satan is using. We can learn to love the person and not take his attack personally because he is in spiritual darkness and doesn't realize he is being used by the devil. Remember, before you were saved you were also a child of the devil and thought the same way.
5. Pray for him and your family daily.
The effective prayer of a righteous person can accomplish much. God wants everyone to be saved, not wishing that any should perish but that all should come to repentance (1Tim 2:4, 2 Pet 3:9). Your prayers will make it easier for him to yield to God and more difficult for him to continue in rebellion. Be prepared, however, for things to get worse before they get better.
If a person will not willing come to Jesus, many times his whole world will fall apart as God starts shaking the idols in his life. He may start taking his frustration out on you, but just realize that this is God making him dissatisfied with the things of this world.
6. Submit to him as to the Lord. (Eph 5:22, Col 3:18, 1Pet 3:1).
You are to recognize the husband's authority over you even if he is not saved. God

7. Be Patient!
It may take some time for God to renew your marriage, but look at God's timetable, not yours. Continue to pray because God is listening.