Who is the third segment of humanity Paul addresses beginning in Romans 2:17?

Les explains that the prosecuting attorney now moves to the third segment of humanity, and that is the religious person. He stresses that religion is man's attempt to somehow please God, and it prompts hatred, precipitates war, and takes people down the dark path of legalism. Christianity, by contrast, is never a religion; it is God reaching down in mercy and grace to a lost human race. Paul uses religion in a bad light when he says he was saved out of the Jew's religion, because he was religious and hated the very name of Jesus of Nazareth as a religious person. In these succeeding verses, Paul is dealing with a religious Jew, the primary religion Paul had to deal with. In Romans 2:17, Paul says, "Behold, thou art called a Jew, ye rest in the law, make us thy boast of God."