"God hath chosen the foolish things of the world to confound the wise; and God hath chosen the weak things of the world to confound the things which are mighty; and base things of the world, and things which are despised, hath God chosen, yea, and things which are not, to bring to nought things that are: that no flesh should glory in his presence."
1 Corinthians 1:27-29

Matthew 1:3 Thamar - base things
Matthew 1:5 Rachab - things which are despised
Matthew 1:5 Ruth - weak things
Matthew 1:6 of her (Bathsheba) - foolish things
Matthew 1:16 of Mary - things which are not

Read Part 1, Part 2, Part 3.