Who are the Majus? And was there a group among them that believed in the oneness of God Almighty, and another that disbelieved in Him?

The Majus (Zoroastrians) are fire worshippers. They believe the world has two origins: light and darkness. They are among the worst types of polytheists, and there are no believers among them. Allah the Almighty mentioned the Majus among the nations He will judge on the Day of Resurrection. As for the Sabeans, they are divided into two groups: the righteous monotheistic Sabeans and the polytheistic Sabeans.