“Why does God do things this way? Why is he willing to be involved with such an array of dubious characters? Look at the women who appear in the genealogy of Jesus, as recorded by Matthew. Front and center there is Tamar, the Canaanite mother of Perez and Zerah. Then there is Rahab, who didn’t just dress up like a prostitute; she really was one! She too found a place in the ancestry of our Lord as she was rescued out of Jericho and brought into the covenant community. Next there was Ruth who, for all her worthiness, was still the Moabitess, a despised foreigner. Finally there was Bathsheba, the mother of Solomon and former wife of Uriah. That is quite a collection of family portraits!
Nor are the men in the family tree of Jesus any better. After all, it was Judah who slept with Tamar without any qualms, all the time thinking she was a prostitute. It was David who arranged for Bathsheba’s seduction and Uriah’s murder. In addition, in the list of Jesus’ ancestors is Manasseh, the greatest idolater among the kings of Judah. Manasseh is the one whose sins were so great that from then on the exile of God’s people was a foregone conclusion. 
Together, these men and women make up a remarkable procession of the great unwashed. Why would the Lord Jesus, who could have chosen to be descended from anyone at all, choose to be descended from such a soiled line?
Matthew explains Jesus' ancestry in the next section of his Gospel. The angel told Joseph, ’You shall call his name Jesus, for he will save his people from their sins.’ As Jesus himself put it, 'The Son of Man came to seek and to save the lost.' He came to rescue sinners, people like his own ancestors, people like us…” Ian Duguid