Sabellianism

In Christianity, Sabellianism in the Eastern church or Patripassianism in the Western church (also known as modalism, modalistic monarchianism, or modal monarchism) is the nontrinitarian or anti-trinitarian belief that the Heavenly Father, Resurrected Son, and Holy Spirit are three different modes or aspects of one monadic God, as perceived by the believer, rather than three distinct persons within the Godhead—that there are no real or substantial differences among the three, such that there is no substantial identity for the Spirit or the Son.

The term Sabellianism comes from Sabellius, who was a theologian and priest from the 3rd century.

Meaning and origins