The Council of Nicea I (325)—the first ecumenical council—is an important turning point in the history of Christianity. It was at this particular council that the very bases of the Christian theology were founded—anathematizing one of the main controversial streams of that time, Arianism. The Council of Nicea I has had an extraordinary place in Muslim refutations of Christianity. This historical event was scrutinized not only in the context of Jesus’ divinity but also—and most especially after the 19th century—within the question of canonization process of the Bible. This article aims to highlight various essential critical points of these sources dealing with the Council of Nicea I.