The usual claim is that doctrines like the Trinityi or forensic Justificationi by faith alone are "new" doctrines. That is, that these doctrines didn't exist at the time of the apostles or within the early Church. Depending on the honesty of the individual, the claim will be that these and other doctrines are completely new doctrines or that they are "developed" doctrines. By developed, they usually mean that the doctrines were there all along in the Bible but had to be better developed or understood by subsequent generations of Bible readers. read more

read more: Does Christianity Contain 'New Doctrines'?