Matthew 1:18-19

Joseph was a righteous man–What made Joseph righteous? It was certainly not self-righteousness. He was not a strict adherent to the law. The legal codes for his day called for him to public disgrace Mary and make an example. This humiliation would deter future indiscretions by other women. The legal code called for Mary’s execution. Deuteronomy 22 explains that if a man discovers that his wife is not a virgin, "She shall be brought to the door of her father’s house and there the men of her town shall stone her to death. She has done a disgraceful thing in Israel by being promiscuous while still in her father’s house." According to Deuteronomy the righteous thing for Joseph to do at that moment would have been to fulfill that command. But the righteousness Matthew has in mind differs from the righteousness proposed in Deuteronomy. It involved compassion over punishment; humanity over legalism; and trust over retribution.