I am reading the works of the Apostolic fathers and it amzes me the difference in what they wrote VS the teachings of Paul in his letters and the teachings of Peter, James and the Gospels.
SOme of the stuff is the same, obviously, but already you can start seeing the development of doctrine that was not present in the works of the Gospels or the apostles.
But let's not forget that most of what the Fathers wrote and thought did not make it into official church doctrine.
"As elemental Trinitarianism of the NT period has to be distinguished carefully from the gradually emerging Trinitarian dogma, so must Trinitarian dogma (doctrine in the strictest sense) be distinguished carefully from Trinitarian theology. The dogma in its preparatory stages had been merely theology: efforts on the part of individuals and schools to interpret and understand revealed mystery. Then, as certain of these efforts became assimilated through authoritative decision into the teaching of the Church, some of what had heretofore been theology was from now on also dogma of faith. But note some; for much else - in Tertullian and Origen, Athanasius and the Cappadocians, Augustine, Anselm, Aquinas - would never receive such ratification, never attain such clear-cut status as Christian doctrine. (Catholic Encyclopedia, 302)"