This is an interesting charge. When and by whom are relevant questions. If the early Church was corrupted, what were the corruptions, when did they occur, and by whom? Additionally, what is the correct teaching, and according to whom?
Additionally, if Jesus’s teachings were passed by the Apostles and the disciples, which Apostles or disciples passed the wrong information?
Some have claimed St. Polycarp, student of John the Beloved, taught non-Biblical teachings. Aside from the fact the Bible wasn’t assembled and accepted until 397 and 419, there is nothing to suggest otherwise, except the beliefs held by the accusers.
again-
most of the new testament is written to correct error in the early (first century church)
some of the people who introduced and practiced the error are ACTUALLY listed in the text of the new testament
so- the presence of error is not a surprise, especially 150 or so years later
This is an interesting charge. When and by whom are relevant questions. If the early Church was corrupted, what were the corruptions,