👉 Arianism is a religious doctrine that holds that God is one person, or the Trinity. This doctrine is based on the belief in three persons of the Trinity - Father, Son and Holy Spirit. According to Arianism, Jesus Christ is not the only being who exists in the universe, but rather He is one with the Father and the Holy Spirit. This idea has been challenged by other religious traditions and has led to a split between Eastern Orthodox Christianity and Catholicism.