Consubstantiality, a term derived from Latin: consubstantialitas, denotes identity of substance or essence in spite of difference in aspect.
It appears most commonly in its adjectival form, "consubstantial", from Latin consubstantialis, and its best-known use is in regard to an account, in Christian theology, of the relation between Jesus Christ and God the Father.
The Trinity (Latin: Trinitas, lit. 'triad', from trinus 'threefold') is a Christian doctrine concerning the nature of God, which defines one God existing in three coeternal, consubstantial divine persons: God the Father, God the Son (Jesus Christ) and God the Holy Spirit, three distinct persons (hypostases) sharing one essence/substance/nature (homoousion).
In Christianity, the doctrine of the Trinity states that God is a single essence in which three distinct hypostases ("persons"): the Father, the Son, the Holy Spirit, exist consubstantially and co-eternally as a perichoresis. Islam considers the concept of any "plurality" within God to be a denial of monotheism. Monotheism in Islam, known as Tawhid, is the religion's central and single most important concept, upon which a Muslim's entire religious adherence rests. Shirk, the act of ascribing partners to God – whether they be sons, daughters, or other partners – is considered to be a form of unbelief in Islam and is considered the worst sin in Islam. The Quran repeatedly and firmly asserts God's absolute oneness, thus ruling out the possibility of another being sharing his sovereignty or nature. In Islam, the Holy Spirit is believed to be the angel Gabriel. Muslims have explicitly rejected Christian doctrines of the Trinity from an early date.