But it was OK in the Old Testament, wasn’t it?
David, and all other men in the Old Testament up to and including the Jews in Jesus’ day who either divorced their wives and took another or added another wife to their already intact relationship would today be guilty of adulterous polygamy under the Atonement. This was not the case under the Old Covenant, however. Jesus tells the religious leaders that Moses wrote this law allowing divorce because of the hardness of people's hearts. Who did Jesus say wrote that law? God? No, Moses. Jesus says it was not this way from the beginning. In other words, the separation of spouses joined by God is not God's will for married couples, period. He says that Moses wrote the law, the inference is with the allowance of God. Why allow such a thing? It seems reasonable to interpret His explanation to mean this was allowed to be written because He knew that people were, to put it plainly, stubborn, sinful jerks and since they lived among heathen lands who practiced this and they were