Commentary: In Matthew 19:3-9, the Pharisees, who clearly disagree with Christ's teaching about marriage and divorce ask why Moses had given the commandment regarding how to obtain a divorce that Jesus references in Matthew 5:31. They want to know why, if marriage was as binding and lifelong as Jesus taught, did "Moses command that a man give his wife a bill of divorcement and send her away?" This is an important turn of phrase. Deuteronomy 24:1-4 does not contain a command to obtain a divorce, it regulates divorces if they occur. Christ points this out, by telling them that "Moses permitted you to divorce…" not commanded. Jesus then goes on to explain why this was permitted – "because your hearts were hard". In other words, because after the fall men were prone to sin and because of this sin divorces would occur, but not that they should occur. He drives this point home, that it was not so from the beginning. Had not the fall occurred, sin would not have entered in and marriages would have remained indissoluble.

Christ goes even further in showing under what circumstance sin makes divorce possible, namely marital unfaithfulness. He then prohibits divorce under other circumstances by saying that all divorces for other reasons are illegitimate, and thus if a spouse remarries following such an illegitimate divorce, they are guilty of adultery, for the original covenant bond of marriage had not been severed in this case.

The word translated in the above verse as sexual immorality is the Greek word porneia, which is usually rendered fornication. Here again the Lord’s choice of words is important, for if Christ had wanted to say "except for adultery" he could have done so. The Greek word for adultery is moikeia. His reasons for not using moikeia have been an issue for debate even within the reformed community. Some have inferred that by not using the word for adultery (which would mean sexual sin within the marriage covenant) Christ was indicating circumstances in which that marriage covenant had not yet come into being, (i.e. sexual sin during the engagement period). This thesis however is doubtful.

It is likely that what porneia does refer to is sexual sin of any and all sorts, by both married and unmarried people, therefore fornication is given as a reason for the dissolution of an engagement and divorce. Also, the scope of sexual sin is expanded outside of just intercourse with a third party during marriage to include all sexual relations outside of the marriage covenant.

Once again, it is worth noting that Christ does not frame his admonishment in terms of a command to divorce. It is clear that he is outlining the only grounds under which it is acceptable to divorce, not commanding that if the grounds in which a divorce may take place are fulfilled, that a divorce must take place. As Murray says: "It does not intimate… that the man is obligated to divorce his wife in the event of adultery on her part. It simply accords the right or liberty."11 Again we see that there is no positive command (especially in the way in which the Pharisees framed their question) to divorce. This reinforces the teaching that we see again and again in the bible, that divorce is something that has come about because of sin.

To quote Jay Adams, "God did not originate the concept as part of His order for society. Divorce, then, is a human innovation."12 Because it has happened, God has set forth regulations that restrain the circumstances in which divorce may occur, but we grievously err if we assume that we are ever presented with a positive command to divorce.

This is not the only passage in the gospels where Jesus discusses divorce. Discussions of divorce also occur in Mark 10:11-12, Luke 16:18, and Matthew 5:31-32. In all cases the teaching of our Lord regarding divorce is consistent – with one critical difference. Only the passages in the gospel according to Matthew contain the exceptive clause "except for marital unfaithfulness (porneia)." Both Mark and Luke simply say that everyone who puts away his wife and marries another commits adultery.

Since I believe it would be intellectually dishonest to ignore the omission at this juncture, I will readily admit that I find the explanation given by Loraine Boettner to be the simplest and most plausible:

The Gospels do not always give our Lord’s teaching in full, and in this instance as in numerous others Matthew simply gives a more complete account. Compare, for instance, the fullness with which Matthew reports the Sermon on the Mount, three full chapters, 5, 6, 7, and Luke’s abbreviated account given in thirty verses (6:20-49). The accounts concerning the baptism of Jesus, the crucifixion, the inscription on the cross, and the resurrection, are given in greater detail by Matthew than by Mark or Luke. Most commentators take the view that there is no conflict between Matthew and Mark and Luke, but that Matthew has simply given a fuller report.13

If we assume, and it seems likely, that Matthew simply gave us more detail as to what Christ actually said, the practice of zeroing in on Matthew when examining the Lord’s teaching on divorce is extremely wise.

So we see therefore that Christ again reiterates the fact that divorce is the result of sin, is never good or commanded, but is permissible in the case of adultery.