Jesus then moves on to the case of adultery:
‘You have heard that it was said, “You shall not commit adultery.” But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart. If your right eye causes you to stumble, gouge it out and throw it away. It is better for you to lose one part of your body than for your whole body to be thrown into hell. And if your right hand causes you to stumble, cut it off and throw it away. It is better for you to lose one part of your body than for your whole body to go into hell. (Mat 5:27-30)
Under the law of Moses, adultery is the wrongdoing of a man against another man, and of the man’s wife against the same man. Accordingly, a married man taking an additional wife or otherwise having sexual relations with another woman (neither being any else’s wife) does not commit adultery (e.g. see Pr 6:20-35). However, the practice of polygamy had declined and the ideal of monogamy had become stronger by the time Jesus taught. Consistent with his earlier disclaimer, Jesus did not come to abolish the law but to perfect it, particularly concerning original wrongs such as adultery. Jesus raises the standard of marriage to monogamy and teaches the command ‘You shall not covet your neighbour’s wife, or his male or female servant’ (Ex 20:17) encompassed, as adultery, every desire for any other woman than his wife.
After teaching the perfect standard of his law concerning marriage obligations, Jesus moves on to the permissible responses on breach of such obligations.
‘It has been said, “Anyone who divorces his wife must give her a certificate of divorce.” But I tell you that anyone who divorces his wife, except for sexual immorality, makes her the victim of adultery, and anyone who marries a divorced woman commits adultery. (Mat 5:31-32)
The law of Moses provided for divorce as the husband’s remedy for breach of marriage obligations by the wife. The result was that the marriage was dissolved, and the spouses were each free to marry another. However, if a divorced woman married another man, and then he died or divorced her also, she could not re-marry her original husband (Deut 24:1-4).
There were two schools of thought at the time of Jesus on the adequate grounds for divorce:
If a man marries a woman who becomes displeasing to him because he finds something indecent about her, and he writes her a certificate of divorce, gives it to her and sends her from his house … (Deut 24:1)
Some held that the ‘something indecent about her’ was strictly sexual immorality, while others construed it broadly (see Mat 19:3-12). The teaching in Mat 5:32 makes a different point: in the case where a man divorced his wife not on the grounds of sexual immorality, she is innocent of sexual immorality at the time of such divorce, but he becomes the cause of her sexual immorality in the form of adultery when she, as a result, gives herself to another man.
Two issues of translation and interpretation arise here:
1. The words translated in the NIV ‘makes her the victim of adultery’ are literally ‘makes her commit adultery’ – although the divorce not on the grounds of sexual immorality is a wrong against the wife, Jesus does not rule that such a wrong is adultery, he says it causes her to commit adultery. The only sensible way to understand this ruling is that she commits adultery when she gives herself to another man after being sent out of her husband’s house (as indicated by ‘anyone who marries a divorced woman commits adultery’).
2. The words translated ‘except for sexual immorality’ in the NIV may appear to suggest that Jesus is making a law prohibiting divorce by the husband and remarriage by the wife with an exception: where the wife does commit sexual immorality, a man may then divorce his wife, and she may re-marry. However, this is not correct in two ways:
a. the ruling given applies to the case stated: the case where a man divorces his wife ‘except for sexual immorality.’ The word translated ‘except’ would be better translated ‘without.’ That is to say, Jesus is identifying the case of the husband who divorces his wife without the wife having committed sexual immorality and ruling on that case, and does not rule on the case where the husband divorces his wife on the grounds that she has committed sexual immorality. (The same applies to Mat 19:9)
b. The ruling about ‘marriage’ to the divorced woman being a form of adultery is a separate case ruling and therefore applies to all cases of ‘marriages’ to divorced women regardless of the grounds of their divorces (as shown by the cases below).
For the sake of completeness we must consider other cases:
1. The case where the wife does commit sexual immorality, and then she is divorced by her husband and takes another man. Although this case is nowhere expressly covered in the New Testament, it is clear she is not free to remarry while her husband lives because she is a divorced woman, so the second case ruling of Mat 5:32 still applies to her (see also Rom 7:2-3, 1 Cor 7:10-11, 39). However, it is fair to say that the husband does not cause her to commit adultery in the sense Jesus referred to, as she had already caused this herself before her husband divorced her. However, he may cause her to keep on committing adultery if he marries another and thereby will not take her back if she repents.
2. The case of a husband who divorces his wife on grounds of her sexual immorality, is he free to remarry? This is prohibited regardless of the cause of the divorce in Mark 10:11 and Luke 16:18.
3. The case of a husband who divorces his wife not on grounds of her sexual immorality, is he free to remarry? Prohibited expressly in Mat 19:9, and regardless of cause in Mark 10:11 and Luke 16:18.
Although under the law of Moses a woman cannot divorce her husband, under Roman law she could. Jesus covered that case in the same way in Mark 10:12 concerning the woman’s adultery in re-marrying.
It is therefore clear that the grounds for divorce are irrelevant to the question of remarriage while the other spouse remains alive. This is why the disciples said ‘if this is the situation between a husband and wife, it is better not to marry’ (Mat 19:10) – this is a hard teaching for many.
So, having now analysed the legal cases we may proceed to identify the logic and legal principle behind all these cases. This can be found by looking at the cases from the point of view of the innocent spouse: the innocent wife divorced by her husband not on the grounds of her committing sexual immorality, and the innocent husband who divorces his wife on the grounds of her sexual immorality. In both cases the innocent party is not free to re-marry. In both cases, taking another man or woman is ruled to be adultery. The critical legal principle is therefore this: the first wrongdoing of one spouse does not justify the later wrongdoing of the other innocent spouse. All adultery is prohibited, and proper legal procedure and adequate legal cause does not excuse it.
We shall now briefly cover the other legal rule from the law of Moses on adultery: the command to stone adulterers. Although Jesus does not here explicitly abolish this law he implicitly does by discussing only the legal remedy of divorce in the Sermon on the Mount. The teachers of the law were practically opposed to the death penalty for any wrongdoing, and although they supported it in principle they abolished in practice with extreme evidential and procedural requirements. At the time of Jesus they also required Roman approval to legally execute anyone. For this reason Jesus had no reason to discuss this law in the Sermon on the Mount.
However, this is indeed a case where Jesus took a different position, in principle, from the law of Moses, and for this reason the teachers of the law tried to trap him in the incident of the woman caught in adultery (John 8:1-11). In this case, Jesus gave an answer that, while invoking the procedural requirements of the law of Moses (Deut 17:7) to stop the illegal honour killing, he also should be understood to have taught that to stone her would be a sin regardless of compliance with legal and procedural justice (John 8:7).
The case of Joseph’s intended divorce is also instructive. Joseph appeared to have suspected Mary of adultery and he intended divorce only, and a quiet one at that:
Because Joseph her husband was faithful to the law, and yet did not want to expose her to public disgrace, he had in mind to divorce her quietly. (Mat 1:19)