All modern day Christian faiths can trace their roots to the same Christian church that existed for 1,000 years after Jesus Christ's death. In 1054, the Great Schism broke the church into two branches: The Roman Catholic Church (from which Martin Luther broke during the Protestant Reformation of 1517) and the Eastern Orthodox Church.One major cause of the schism is what's known as the Filioque clause. In the Nicene Creed where it reads "We believe in the Holy Spirit ... who proceeds from the Father," the amended Roman Catholic version reads "We believe in the Holy Spirit ... who proceeds from the Father and the Son."