'''Sabellianism''', also known as ''modalism'', is a heresy which states that the Father, Son and [[Holy Spirit]] are different modes or aspects of one God, rather than three distinct persons. Modalism's unitarian view of God is commonly described by an analogy: water in its three states of ice, liquid, and steam appear to be different substances, but in reality they all are composed of the same chemical compound, H20. Likewise, for Sabellians or modalists God the Father, Christ, and the Holy Spirit appear to be three distinct persons, but they are really just different manifestations of one solitary God.
The heresy is attributed to Sabellius, who taught a form of this doctrine in Rome in the third century. [[Hippolytus of Rome]], an early Christian writer and [[martyr]], knew Sabellius personally and mentioned him in his Philosophumena (or ''Refutation of all Heresies''). He knew that Sabellius disliked Trinitarian theology, yet he called Modal [[Monarchianism]] the heresy of Noetos, not that of Sabellius. Sabellianism was embraced by Christians in Cyrenaica, to whom Demetrius, Patriarch of Alexandria, wrote letters arguing against this belief.