Should a Christian marry a non-Christian? For many Christians this isn't a theoretical question, but one of burning personal urgency. And it's often particularly women who feel this, because of the gender imbalance in churches: typically, women will outnumber men by nearly two to one. So any woman who wants to marry and have children is potentially in a very difficult position. We all like to believe in love and romance, but realistically the pool of potential husbands is smaller in church than out of it. So if a church teaches that marriage must only be between Christians, it bears a heavy responsibility to women like this.

Some Christian teachers take a very strong line on this. They argue that the Bible forbids marriage to those outside the faith and that any marriage to a non-believer is a sin that requires repentance. Others argue that the effects on the believer's faith are likely to be negative and lead to spiritual compromise.

But what does the Bible actually say?

In the Old Testament

God's people are commanded not to marry non-Jews. Deuteronomy 7:3-4 says of the people the Hebrews were to conquer: "Do not give your daughters to their sons or take their daughters for your sons, for they will turn your children away from following me to serve other gods, and the Lord's anger will burn against you and will quickly destroy you."

This rule was more strictly enforced in some periods than in others. In Ezra 9-10 there is a sad story of men who had married foreign women, and in some cases having children with them, repenting of their sin and divorcing them. We aren't told what happened to their wives and children. Numbers 25:1-17 tells of how Aaron's grandson Phinehas killed an Israelite man and a Midianite woman with a single thrust of a spear as they were having sexual intercourse.

The stress in the Old Testament was on keeping the race pure in order to keep the faith pure. However, of course, Old Testament laws specific to Jews – as opposed to the moral laws binding on everyone – are not applicable to Christians (Acts 15:19-20).

In the New Testament 

Two texts are frequently cited. One of them is 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?"

Claiming Paul was specifically commanding believers not to marry non-believers on the basis of this verse, however, is problematic. Look at the verse in context and he is not talking about marriage at all. He seems to have a wider problem in mind – more literally, the command is to "stop yoking yourselves to unbelievers". In fact it's an agricultural metaphor. The picture is of two different kinds of animals – an ox and a donkey, for instance – yoked to the same plough. One might be bigger and strong than the other, and will dominate the weaker one. But does he mean business partnerships? Shared meals? Legal cases? This is one of those cases in Paul's letters where we only have one half of the conversation and have to guess the other half.

A suggestion in The Expositor's Bible Commentary is that it expresses the principle: "Do not form any relationship, whether temporary or permanent, with unbelievers that would lead to a compromise of Christian standards or jeopardise consistency of Christian witness." According to the IVP Commentary, "The specific kinds of partnerships are left unnamed. A principle is merely articulated and understanding of its application assumed." It does say: "Marriage between a believer and unbeliever would certainly be a legitimate application of the command" – but it's very important to realise that this is an application, rather than a specific prohibition. This is not a verse that forbids Christians to marry non-Christians.

The second verse is 1 Corinthians 7:39. This comes at the end of a long section of teaching in which, among other things, Paul tells people who become Christians not to divorce their unbelieving partners. He does not tell Christians they should not marry non-Christians. The NIV translation of verse 39 is: "A woman is bound to her husband as long as he lives. But if her husband dies, she is free to marry anyone she wishes, but he must belong to the Lord." This is a very free translation of the Greek, to put it no more strongly than that: actually Paul says, "she is free to be married to whom she wishes, only in the Lord". The word "in" can mean a number of things. The phrase "only in the Lord" could also be read as saying she must have a good conscience before God in her decision.

So there is no New Testament command unequivocally prohibiting Christians from marrying non-Christians.

However, in everyday Christian discipleship there are potential problems. Some Christians marry people from different faiths altogether. They need to negotiate all sorts of questions, like how they will bring up their children, whether they will attend services in each other's place of worship, and whether they will try to convert each other.

It's more likely that Christians will marry a non-believer. Here, too, there are potential problems. Some people scoff at religion altogether. Their contempt for religion implies a contempt for believers, and that has no place in a marriage. Some are just indifferent, and that can be hard to cope with, too: if a person has a sincere and genuine faith, it's hard to live with someone who doesn't care about it one way or another.

On the other hand, some people are not believers, but are respectful, interested and supportive of a spouse who is, even to the extent of coming to church and taking part in activities.

So, should a Christian marry a non-Christian? Here are three things to consider.

1. There is no specific biblical prohibition against it.

Christians who are adamant that the Bible forbids it are wrong. It's probably true, based on the general trend of his teaching, that Paul would have advised against it, but we have no specific command that says so. We must not make the Bible say things it doesn't say. So if people argue vehemently that Christians ought not to marry non-Christians, we might need to ask whether there's another agenda at work. Perhaps they have a vision of a "perfect" marriage, in which a Christian couple is part of a Christian church bringing up Christian children. But life is sometimes not so tidy, and we must be careful not to diminish someone's marriage – which is still a sacred bond – by implying it's less than ideal.

2. It does throw up extra challenges.

Marriage can be hard at the best of times. The extra strains created when two people don't share the same faith can make it even harder. If one partner is a Christian before they marry, it does at least give them the opportunity to talk through potential conflicts in a way that isn't so easy if someone becomes a Christian when they're already married. These include a Christian needing to find space for prayer, making new friends, and taking time for church activities which may be resented. Pre-marriage preparation can be very helpful in this respect. There's also the problem of spiritual loneliness, which some Christians who've married non-Christians do experience. Faith is such an intimate part of the lives of believers that it can be very hard to live with someone who has no idea what it really means. From a pastoral point of view, it's a risk. 

3. We should trust in God.

Some marriages between Christians and non-Christians fail or are unhappy. Some marriages between two Christians fail or are unhappy, too. But God blesses marriage as an institution. For two people to love each other and share their lives together is a holy and precious thing. To argue, as some do, that their marriage is somehow wrong or incomplete because they don't share a Christian faith fails to take into account the common grace God gives to everyone.

So, should Christians marry non-Christians? We need to be very careful not to go beyond what the Scriptures say, but certainly the scriptural trend is in the direction of "no". All things being equal, it is likely to be unwise. But that's very different from saying it's a sin, and God can still bless such marriages with deep happiness.

Follow Mark Woods on Twitter: @RevMarkWoods