The Apostle Paul is aware that the newly planted church in Rome was made up of both Gentiles and Jews, and so some of the things he was writing would be received differently by each group. After unloading pretty heavily on the wayward pagan world in chapter one, he is quick to tell the Jews that they are no better. It's a lesson for all Christians that without Christ, we all stand condemned. We need to be Gospel confident, but with a posture of humility.