Christianity, which originated in the Middle East in the 1st century AD, has been one of the major religions of the region from 4th-century Byzantine reforms until the Arab Muslim conquests of the mid-to-late 7th century AD. Christianity in the Middle East is characterized by the diversity of its beliefs and traditions, compared to other parts of the Old World. Christians now make up 5% of the Middle Eastern population, down from 20% in the early 20th century.