After Judaism, Islam is the non-Christian faith tradition closest to communion with the Catholic Church. The Catholic Church teaches that, like us, those who practice the religion of Islam profess to worship the one and merciful God, who will judge mankind on the last day, though they have a different and, at times, erroneous conception of Him. But while we share many commonalities with our Orthodox and Protestant brothers and sisters and with the Jewish people, Islam differs much more significantly from Christianity.