Jews in Jesus’ day believed that divorce was lawful — the only debated issue was the proper grounds for it. Jesus explained that Moses permitted divorce because of the hardness of human hearts: in other words it was a concession to the human condition and contrary to God’s plan for us. This accommodation to divorce was used to bring order in a society that had disregarded God’s will, but it was not the standard, which God had originally intended for his people. The purpose of Deuteronomy 24:1, which sanctioned divorce, was not to make it divinely acceptable but to reduce the hardship of its consequences.
Jesus takes his interrogators back to the beginning of creation, to God’s original purpose. God instituted marriage as a great unifying blessing, bonding the male and female in his creation. Jesus grounded the sanctity of marriage in the authority of God, whose ‘no’ to divorce safeguards against human selfishness, which always threatens to destroy marriage. In Jewish practice divorce proceedings were brought by the husband, not by the woman or a judicial court — husbands were divorcing their wives on whim. A simple declaration of divorce could not simply release him from the divine law of marriage and its moral obligations.
Marriage is God’s gift and it is a vocation. It can seem difficult, even impossible, to bind oneself for life to another human being; but marital love reflects something of God’s definitive and irrevocable love.