I'll try to answer from a biblical perspective.
Apostasies occured from the beginning of the Christian congregation. The Roman church continued to propogate beliefs that were not from the inspired scriptures. As I mentioned earlier, I believe the trinity belief is incorrect, hence an example of apostasy. Forbidding men to marry, scripturally, is a sign of a false teaching.
Since I do not recognize the universal church of Catholisism as having been part of true Christianity, I believe the council was not a part of a true Christian arrangement.
I think the corruption of the church was gradual but constant. It appears that the Church was the only vehicle around, whether it was being corrupted slowly or not.
When you look at the shameful history of the Popes, you cannot make me believe these vicars were representing God!