Start with Part 1 here.
Paul’s ethical teachings were based on two sources: the Old Testament and the words of Jesus. It’s important to consider these sources, and determine if Paul disagreed with either source on the subject of divorce and remarriage. I conclude that he does not.
Background
In Corinth, Paul faced a different problem than Jesus. Paul’s readers were under Roman law, not Old Testament law. Under that law, either the husband or the wife could divorce a spouse simply by declaring themselves to be no longer married (source/original, source/original). One spouse declares (or even just decides) no longer to be married, and then either moves out or sends the spouse away, depending on who owns the house. Note that the divorcing spouse does not need to provide any grounds for the divorce; in this way it is also similar to today’s no-fault divorce, in much the same way as the Jewish “any cause” divorce.
This was very different than the Law which Jesus and the Pharisees were discussing; even the “any cause” divorce required a written document.
Summary
Paul taught his readers that Christians should not instigate a divorce by this simple manner of announcing-and-separating. However, if a Christian were divorced by a non-Christian, that Christian was free to remarry, but only to another Christian. Paul also appears pragmatically to allow a Christian divorced by another Christian also to remarry.
Divorce by separation is forbidden
In 1 Corinthians 7.10-11, Paul charges his readers not to separate. (Again, separation in Roman law is the same as divorce; separation just is divorce. See the sources above.) Because of the terms Paul used, the type of divorce he refers to in his letter appears to be the one mentioned above: divorce by separation. Paul (citing Jesus) disallows this. Paul recognizes, however, that not everyone will obey this command, so if one spouse separates, the spouse should remain unmarried with the hope of reconciliation. Paul specifically addresses the woman who separates, but we can assume he intends this to apply to the man as well.
Divorce by separation need not be resisted
Paul then addresses a situation which Jesus did not face: what if one spouse is a Christian and the other is not? Paul’s instruction, which he claims as his own because (as just stated) Jesus never faced this situation, is that the Christian should not seek to separate. He rules, however, that if the non-Christian chooses to separate, then the Christian should allow it.
This seems to be a contradiction: Paul first says not to separate (verse 10), and then says separation is allowed (verse 15). Paul makes it clear that he is speaking to believers married to unbelievers in verse 15; we can avoid the contradiction by assuming he is speaking to a Christian couple in verse 10.
If this is correct, then Paul is telling his readers that as Christians, they should never initiate a divorce, but if the partner chooses to divorce, the Christian is not under an obligation to strive to prevent it. Is that only for non-Christian partners? Is Paul allowing a divorce in the case of an unbeliever but not if both spouses are believers? Paul leaves us with two cryptic statements to aid us in understanding him: the Christian is not “enslaved” and “God has called you to peace.” What are we to make of these statements?
What does it mean to be “not enslaved”?
Paul claims that a person whose partner has left is free; that is, “not enslaved.” If that person is free, in what way is that person free? It seems that the plain reading is that the person is free from the failed marriage. To be free from the marriage would entail that the person is also free to remarry; otherwise, the person is hardly free. This seems to be the straightforward reading of the term “not enslaved.”
Not all agree with this interpretation. Some interpreters claim that the term means instead that the person is not enslaved to pursue reconciliation with the departed spouse, but must remain unmarried until that reconciliation occurs (source/original). This is an odd phrase for Paul to use if he wanted to communicate this truth. Think about it: the claim here, apparently, is that Paul is telling his readers that pursuing reconciliation is, in fact, enslavement. It’s difficult to deny that (according to this interpretation) Paul is really saying that the desire to preserve a marriage is enslavement, the hope for reconciliation is slavery, and that praying for the repentance and return of a wayward spouse is bondage.
The same interpreters who deny the right of remarriage claim that a person who is married is never actually free from the marriage until the spouse has died; that is, the marriage is still in effect regardless of actions by either party. These interpreters affirm that “a person’s marital bond persisted despite the other spouse’s behavior” (source). This means the faithful wife in a failed marriage is to be forever single, unable to demand the return of her dowry, and forbidden from remarrying while her ex-husband is alive. To have one’s choices removed, to be required to submit to the will and actions of another, to be unable to live one’s life as one pleases — this sounds exactly like enslavement. For Paul to claim that this is actually freedom rings hollow.
Let’s examine this further. According to these interpreters, “being enslaved” means attempting to reconcile with a partner who continues to resist. It means continuing to act as though you are married, even when your partner has moved on. It means remaining unmarried even if your partner has moved on to someone else. Being forced to live at the whim of someone else, not having the freedom to make your own decisions…that does sound like enslavement.
However, not being enslaved means…virtually the same thing! Minus the attempts to reconcile, you must still act as though you are married, you must remain unmarried even when your partner moves on, and you are still living at the whim of someone else.
The alternative is very different, however. When we hold that the faithful partner whose spouse has separated is not required to act as though he or she is still married, this is the very definition of “not enslaved.” The faithful partner has made sincere and repeated attempts to reconcile, which the separating spouse has rejected. The marriage bonds have become chains, locking the faithful partner to someone who has no intention of reconciling, and may have gone on to marry another. Paul’s choice of words is appropriate: in this case, the person would truly be enslaved, and he instead pronounces them free.
Note that this interpretation is not based on sympathy: we don’t come to this conclusion because we are sorry for the deserted spouse, or we feel bad that he or she is trapped due to circumstances beyond his or her control. Instead, we are taking seriously Paul’s pronouncement of freedom for persons in that situation; the deserted spouse is truly not enslaved.
God has called you to peace
The plain meaning of this phrase seems to be that the deserted spouse should not feel compelled to pursue reconciliation with a former spouse who has separated. It has an additional nuance, which is the recognition by Paul of the reality that under the current divorce laws, the deserted spouse truly has no recourse, especially if the deserting spouse is not a Christian. His is a very pragmatic response, acknowledging the reality of his readers’ situation and the weakness of humanity.
Paul has ruled regarding the dissolution of a marriage between a Christian and a non-Christian. The question before us now is this: what about a dissolution of a marriage between believers? Yes, Paul has said that if a spouse separates, that spouse should remain single in hope of reconciliation. Paul, however, must be aware that there are any number of situations where the separating spouse does not reconcile, and perhaps marries another. What is the deserted Christian to do?
Paul is not explicit, but he has left us guidelines: the deserted spouse is not to be enslaved by the marriage, and should be able to live in peace. We can conclude that if a marriage to an unbeliever can result in freedom (see the above section on “not enslaved”), the same is true for a marriage to a believer.
To those who question this assumption, pointing out that the text does not explicitly say this, I agree. I’ve already made two other assumptions: 1) verses 10-11 are speaking of two Christians who are married; and 2) verses 10-11 apply to men as well, even though only women are mentioned specifically. A text needn’t be specific in order for us to draw certain conclusions.