A Christian's life is in constant opposition to the non-Christian outlook and agenda, and as long as a person is a non-Christian, he lives every moment of his life as a rebel against God's kingdom and his people. Therefore, on this spiritual level where things really count,the Christian and the non-Christian maintain a constant hostility against each other. Although this should not translate into physical violence, this does not reduce the enmity between the two. Unthinking people regard physical violence as more dangerous or more worthy of attention, but the conflict on the spiritual/intellectual level runs much deeper, and carries greater long-term influence and significance. This does not mean that you have to be constantly abusive toward unbelievers. However, there must always be a clear awareness of what they are, so that when you interact with them, you will not operate on false assumptions about what kind of people they are and where they stand. Many Christians are often tempted to allow a sense of solidarity with men to override their obligation and allegiance to God. But God is pleased with those who will put him front and center in all that they think and do (Exodus 32:25-29; Numbers 25:3-13; Deuteronomy 13:5-16; Deuteronomy 33:8-11).

A number of hurdles in theology and apologetics exist for many believers because of this – on those issues they stand with men rather than God. Otherwise, there is no reason that a Christian should have any hesitation or difficulty in answering a challenge such as, say, the so-called problem of evil. It has never been a rational problem for Christianity, but when the objection is raised, believers sometimes sympathize with men's bitterness against God, and allow a problem to take root where there should be none. You are generally permitted to associate with unbelievers, but there are biblical restrictions and exceptions, which I cannot enumerate here. In any case, you must no longer behave toward them the way you did before, and you must abandon the idea of maintaining intimate and meaningful relationships with any of them. Since your deepest commitments are now vehemently hostile to theirs, it is no longer possible to have the deepest kind of communication and comradeship with them. Even the closest relationships between Christians and non-Christians must remain superficial. Anyone who disagrees with this either compromises their Christian commitment, or fails to understand what it is to have a truly deep friendship.

This reality finds its most acute expression in the marriage relationship. Now, of course a Christian must not marry a non-Christian, so we are considering a marriage in which one of the two unbelievers converts, or in which a Christian marries a non-Christian in defiance against God's command. Since the marriage relationship is supposed to be the closest possible relationship between two human beings, this is also the closest possible relationship between a believer and an unbeliever, but because such a relationship is doomed to come far short of what marriage is intended to be, it is also the most tragic. In fact, in a relationship where two people are supposed to become one in spirit and in body, these two individuals are divided at the deepest level, torn apart by the vast gulf that separates heaven and hell. This separation is already present and manifest in their daily life, and unless the other person also converts, one day it will become complete and permanent.

In contrast, the marriage vow between two believers is taken from God's own word (Genesis 2, Ephesians 5, etc.) and taken before God as their witness. Their ability to fulfill this vow comes from their constant contact with God's power in sanctification, and their confidence in each other is also derived from this. Just as a Christian relies on the Holy Spirit to sustain his spiritual life, and to grow in knowledge and holiness, he depends on this same power and grace to make progress in his marriage. On the other hand, there is no power and no promise for the non-Christian who takes the marriage vow. He relies on his own moral integrity and ability, and since he has neither of these or at best only an appearance of these, his marriage and all his relationships – like all his thoughts and activities – are without meaning and substance. The question of how much we are to interact with unbelievers is frequently mishandled. People err toward both extremes. There are those who think that we must deliberately disassociate with unbelievers as much as possible, but this extreme is not common in our circle. Rather, there is sometimes a need to correct a misapplication of the teaching that believers are to be "in but not of the world." Some Reformed and Evangelical believers carry this very far, riding on their version of the "cultural mandate," their denial of any "sacred vs. secular" distinction, and the false doctrine of "common grace." This line of thinking is sometimes used to excuse their licentiousness, and their lust for worldly culture, amusements, and associations. But to be "in" the world, or even to be very involved in it, does not mean that we are to embrace and befriend it.

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Our interest here is whether Christians should shun all immoral non-Christians. Paul gives a negative answer, but this comes within the above context and cannot be universally applied without discrimination or qualification. Also, what reason does he offer? And what does his explanation imply? Again, Paul states that it would be impossible to shun all immoral non-Christians, because all non-Christians are immoral people, and they are everywhere. The only way to avoid them is to leave this world. At least in this passage, he does not say that to shun non-Christians is morally wrong in itself – he states only that it is practically impossible to do so. And at least in this passage, he does not say that to associate with non-Christians is in itself a desirable thing, but only that it is a practical necessity. Therefore, based on this passage, one cannot assert that the opposite of not shunning non-Christians is to befriend them and to have intimate and meaningful relationships with them.

Of course there are other reasons to associate with unbelievers. Besides the practical impossibility of avoiding them in social and business transactions, God has commanded us to bear witness to the gospel of Jesus Christ before all people by our words and deeds, through which God will summon to faith those whom he has created and chosen for salvation, and harden those whom he has created and chosen for damnation. But nothing in the entire range of our activities before the world requires us to become intimate friends with unbelievers. And in fact, it would be a spiritual, intellectual, ethical, and practical impossibility to do so – again, unless either the Christian or the non-Christian compromises his deepest commitments, in which case either the Christian is no longer a Christian, or the non-Christian is no longer a non-Christian. Therefore, although it is indeed possible for a Christian to be on friendly terms with a non-Christian on a superficial level, an intimate and profound communion is out of the question.