Christian doctrine is rooted in Trinitarian doctrine. It is the profession that in the One God there is an unbroken unity of essence shared by 3 distinct Persons. These 3 Persons have existed from all eternity in the Godhead, but they are not 3 distinct Gods. That would be "Tri-theism", a belief in three gods. Trinitarian doctrine also teaches that the three distinct Persons of the Trinity never blend with each other in their divine Persons. They are forever distinct from each other as Persons, even though they share the same nature and attributes as the One God from all eternity. Trinitarian doctrine is the highest form of Monotheism possible, and to reject the distinct Persons of the Trinity in the name of "Monotheism" is an attack on Monotheism itself. If you reject the Trinity, be ready to see what you never thought possible in this Trial.