Ruth

Ruth is another woman who is listed in Jesus' genealogy. You can read her story in the book of Ruth.
The basic outline of the story is: Ruth, who is not Jewish, marries a Jewish man when he lives in Moab. This man dies. His mother Naomi decides to go back to Israel. Ruth goes with Naomi instead of staying in Moab and takes care of her. Eventually Ruth ends up marring Boaz and becomes the great grandmother of King David.

Why would Matthew list Ruth in the genealogy? It could be because she was so faithful. However could she have been included because she was not Jewish? In fact if you look at the list of women we know that at least three of the women were not Jewish (Tamar, Rahab and Ruth). And the fourth was Uriah's wife, we don't know if she was Jewish but we do know that Uriah was a Hittite (not Jewish). So could Matthew be hinting already that Jesus' message was going to be for more than just Jews?