Doctrine of the Church has its roots in the early literature of the Christian era. Apostolic Fathers and apologists usually represent the Church as the Holy Communion, the people of God, which he chose in possession. Although it is referred to as the Eternal House of God in the relationship of the Church with its historical background is not always well understood.
The biblical understanding of eternity was formed by the Church in the context of cosmology, mainly within the criticism of Origenism. The question was about choosing between the antique concept of eternal cosmos associated with cyclical understanding of time and the Biblical line vision of history, which was started thanks to the full expression of God’s will.
The antique picture of the universe is dualistic, it involves two co-eternal original: the intelligible cosmos, i.e., impersonal world of ideas; and the world of matter, which is lower, nevertheless equally eternal reality.
In its essence, the intelligible cosmos is static; each of its elements is constant. However, at the level of matter, the universe is in the constant movement, an infinite rotation and self-repeating, which, however, is only an expression of eternity and unconditional necessity of cosmos. The universe, from the point of view of ancient philosophy, can change its shape, what it does, but in its intelligible essence, its being is consistent and endless through time. This dynamic cycle eliminates the question about the origin or beginning of the cosmos and blurs the radical difference between the eternal God and his eternity stressed in the Scriptures, on the one hand, and having the beginning and existing in time universe, on the other.
Fathers and teachers of the Church, beginning with the early Christian apologists, denied any form of dualism, no matter it was Platonic, Gnostic, or Manichaean. They strongly insisted that both intelligible and material universe is not original, it has a beginning, and its existence is bound to the good will of the creator, raised it from non-existence. Therefore, only God may be called eternal and immortal in the true sense of the words. Other beings can possess immortality only because of their involvement in it.
However, early Christian writers still did not clearly express the difference between the inner being of God and his Revelation in the outside, often resulting in confusion of categories of the divine nature and the divine will, ontological and cosmological aspects.
The mystery of the Holy Trinity was seen in the writings of the fathers in the 2nd-3rd centuries BC, mainly in the context of God creating the universe, without regard to Its being in himself. This mixing has been unclear also in addressing the problem of eternity.