Jesus speaks in Mark 10:2–11 about divorce:
And Pharisees came up and in order to test him asked, “Is it lawful for a man to divorce his wife?” He answered them, “What did Moses command you?” They said, “Moses allowed a man to write a certificate of divorce and to send her away.” And Jesus said to them, “Because of your hardness of heart he wrote you this commandment. But from the beginning of creation, ‘God made them male and female.’ ‘Therefore a man shall leave his father and mother and hold fast to his wife, and the two shall become one flesh.’ So they are no longer two but one flesh. What therefore God has joined together, let not man separate.”
This was hard to understand. At least, it was for the Lord’s disciples. Surely the divorce law that God gave through Moses was truly from God! It was practical. It provided for the wife not to be left without financial support. Yet Jesus here went back to talking not primarily about what the sad reality was but mostly about God’s design. Isn’t that just idealism? That really should be baffling. Why would God tell us again about an ideal that could not be?
And in the house the disciples asked him again about this matter. And he said to them, “Whoever divorces his wife and marries another commits adultery against her, and if she divorces her husband and marries another, she commits adultery.”
So the disciples asked Jesus to explain. Why should he theorize – even if he was the Christ – about what ought to be and say nothing practical? Because the truth was plain: it wasn’t just about ideals but really about right and wrong. What is good and what is bad in the Lord’s sight isn’t for ideals. It’s for living.