By the second century, many Christians believed that Jesus was both human and fully divine. This assertion, however, sparked bitter arguments and a theological conundrum in the early church. Christian leaders struggled with a fundamental problem: How would they reject the pagan notion that there are many gods, yet retain the firm monotheism expressed in the Jewish Scriptures? Rabbi Tovia Singer explains that one popular solution was to say that Jesus was actually God the Father himself, who became a human. This idea, often labeled modalism since it argues that the one God has different modes of existence, was attacked because it spawned staggering problems for Christian thinkers.