Why did Joseph want to divorce Mary?

It has been commonly suggested that Joseph resolved to divorce her quietly after hearing of her pregnancy and, presumably, of the adulterous act that must have caused it. This interpretation argues, therefore, that Joseph wants a divorce because he realizes that another man is involved. This view is not without its problems, though.

1. It assumes that Mary didn’t tell Joseph about the angelic messages but instead just left him in anguish over the idea that his betrothed had committed adultery.

2. This view makes rather incomprehensible the fact that Matthew calls Joseph a just man in carrying out a divorce, albeit quietly. The Mosaic law did not look favourably upon divorce (Deuteronomy 24:1–4; see also Matthew 5:31, Matthew 5:32). And this same law prescribed stoning for women who had committed adultery, or were suspected of such (Deuteronomy 22:23–24; Numbers 5:11–31). So we would almost expect that Joseph, as a just man, would solve his problem by quietly bearing the injustice and carrying on with the marriage.

There is another option, though—an exegesis that has existed since the early church (Eusebius, Basil, Ephraem, Theophylactus) but has in recent times resurfaced. J. van Bruggen has argued that Joseph knew that Mary was with child through the Holy Spirit (Matthew 1:18). For are we really to believe that Mary, who sang that beautiful song in the presence of her relative, Elizabeth (Luke 1:46–56), said nothing to Joseph in the ensuing six months? We can assume she shared with her betrothed the news of this appearance of an angel and the wonderful work that God was doing within her. And then Joseph, being a just man (which for Matthew means fearing God and doing his will; see Matthew 10:41; Matthew 13:17, Matthew 13:43, Matthew 13:49; Matthew 23:29, Matthew 23:35; Matthew 25:37, Matthew 25:46) and respecting this mysterious work of the Spirit, is led to conclude that he himself is standing in the way of this work of God, and so he must pull away from Mary and her special future, even if the only option by which to accomplish that is divorce.¹ Notably in this regard, the reason that Joseph opts for divorce is not so much that he no longer wants Mary as his wife, or that he is angry at or disappointed in Mary, but that he is afraid to have her as his wife. This is evident in the word of the angel of the Lord: Joseph, son of David, do not be afraid to take Mary home as your wife (Matthew 1:20). This likely indicates that Joseph was aware that the Holy Spirit had required Mary for the important task of bearing a special child, and he did not dare to press his marital right.² He was looking for an honourable way out. So rather than going to the judges and receiving an official divorce—thereby exposing Mary as an adulteress in the view of people—he could give her a private letter of divorce, which would clear her in the public eye and leave the blame with Joseph himself for leaving his young wife. Mary alone would have the proof that he had divorced her. Joseph was willing to make this sacrifice, since God had clearly shown that he needed Mary for his purposes.