Modalism is a theological concept that describes the nature of the Trinity in Christianity. It asserts that God is a single entity who reveals Himself in different modes or forms, rather than existing as three distinct persons. According to this view, the Father, Son, and Holy Spirit are not separate beings but different manifestations of the same divine essence. This belief contrasts with Trinitarianism, which holds that the Father, Son, and Holy Spirit are three co-equal and co-eternal persons within one Godhead. Modalism emerged in the early centuries of Christianity and has been considered a heretical view by many mainstream Christian denominations.