What do you know about Rahab (beyond the fact that she was a prostitute in Jericho)? Why does Matthew include her name in the genealogy of Jesus? Rahab is a picture of saving faith.
It is a fascinating thing that Matthew has done. He has named 5 women in the Genealogy of Jesus - and they aren't the names one would expect. Most are foreigners, none have a child in what would be considered the 'traditional' way. The first four Tamar, Rahab, Ruth and Bathsheba have children by men who are not their first husband - the last one, Mary, has her child by the power of the Holy Spirit.
The presence of these names in Matthew 1 is an invitation for the reader to look at their stories more closely - and this advent series does just that - considering God's grace to Tamar, Rahab, Ruth, Bathsheba and Mary - and the ramification of God's grace to you and me through his incarnate Son.