In Christianity, the doctrine of the Trinity states that God is a single being who exists, simultaneously and eternally, as a communion of three distinct persons, the Father, the Son, and the Holy Spirit. Within Islam, however, such a concept of plurality within God is a denial of monotheism and foreign to the revelation found in Muslim scripture. 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. The Quran repeatedly and firmly asserts God's absolute oneness, thus ruling out the possibility of another being sharing his sovereignty or nature. There has been little doubt that Muslims have rejected Christian doctrines of the Trinity from an early date, but the details of Quranic exegeses have recently become a subject of renewed scholarly debate.