Modalism is a common false concept of the nature of God.  Essentially, in an attempt to maintain the oneness of God, the Trinity is denied.  Modalism asserts that there is one divine Person who makes himself known in three different ways, i.e., three forms or modes.   Thus, each form or manifestation of God is one way in which he reveals himself.  It is said that the one God revealed himself as the Father in the Old Testament, as Jesus in the Incarnation, and now as the Holy Spirit in the present. Thus, Modalism says that there is only one Being, one Person, made known in three different ways. But this is not a biblical understanding of the Godhead. In Scripture, we are presented with one God who eternally exists as three divine Persons, each fully God, each one distinct from the others, yet one God. This is the Trinity.