Jesus is moving toward Jerusalem.
Divorce is apparently a hot topic in Jesus’ day, as it has been at times in our day. Today I don’t think we worry about it too much.
Men were in control. By the prevailing laws and customs, they could set aside a wife and marry another for almost any reason. Like today. But unlike today, the women could not do the same. They were something like property.
The Pharisees possibly wanted to set Jesus against the men, or possibly they wanted to cause him to speak out against Antipas, as John had done. At any rate, they invoke Deuteronomy 24, but mischaracterize it as a command. Jesus goes back further, to Genesis 2, and corrects their error.
Jesus talks about what we might call today the sanctity of marriage. It is a true joining, not just a sexual thing, It is sanctified by God himself and should not so casually be dissolved. In fact, it isn’t dissolved even by divorce, unless the women committed adultery and caused the divorce. The man who remarries is an adulterer, because he is still spiritually joined to his original wife.
Today, not many would consider such a man an adulterer. And also today, the woman is not without her own leverage in marriage relationships. Jesus would give women much more power than they had in his day.
The disciples display the prevailing culture when they say that marriage without an escape clause doesn’t sound very good. Jesus turns their thoughts around to say that truly, some people need to stay single for the sake of the kingdom.
This teaching, too, has been perverted through the ages.