Romans 1:16

Jews and Christians alike stood against the idolatrous Roman Religions, and Roman officials often confused the two groups. This was especially easy to do since the Christian church in Rome could have been originally composed of Jewish coverts who had attended the feast of Pentecost in Jerusalem (see Acts 2:1ff). By the time Paul wrote this letter to Romans, however many Gentiles had joined the church. The Jews and Gentiles needed to know the relationship between Judaism and Christianity.