It is often suggested that the Egyptian triad was the model for the Christian, though the Christian concept of a total unity does not correspond to the Egyptian concept.
The concept of the Christian Trinity is not defined from the New Testament, rather it belongs to the times of the first Christians. Its background was the troubled disunity of a God acting on earth as a distinct figure without God's omnipotence (i.e. Jesus) and a third emanation of God, a spirit acting within the community of the first Christians (i.e. Holy Spirit). Still, the concept of the Trinity would take centuries to develop, and with many controversies.
The concept of the Trinity had to balance the interests of not making the three as independent gods, nor should they be seen as simply aspects of the one and the same god.
In addition to the three parts of the Triad being decisively mentioned in the Gospels, a challenge for clarification comes from Paul.
1. Corinthians chapter 8The North African theologian, Tertullian, was the first to relate to and define "trinity" sometime around 200.
Before arriving at the final definition of trinity, the early church went through a number of development stages. The need to safeguard monotheism was the main motive in the debates. One early explanation of the three emanations was to define Jesus as subordinate to God, as Origen promoted. A second theory was to define the three as modes of the disclosure of God, all being part of the same being.
It was first late in the 4th century, that the final definition of trinity was set down. At the Council of Nicaea in 325 a hard-to-get definition of Jesus made him both distinct from God, yet of the same substance. At this time, the Holy Spirit still came out as little defined. This long process had involved Athanasius and the Cappadocian Fathers; Basil of Caesarea, Gregory of Nyssa and Gregory of Nazianzus.
Augustine defined Trinity explained that the Holy Spirit was the mutual love between Father and Son.
Christianity has a second trinity, which is weaker in its formulation, yet important with many cults: Jesus, and his mother Mary and father Joseph, often called the Holy Family. Joseph plays an inferior role, it is the mother-son relation which has potency, similar to that of Isis and Horus of Ancient Egyptian religion. As Joseph is a detached figure, in many ways, Osiris of Ancient Egyptian religion is so too.
In the Islamic-linked orientation of Bektashi and partially in Alevism, there is the concept of a trinity, formed between God, Muhammad and Ali, known as wahdat al-wujud, the "Unity of Being".