Were any new doctrines introduced in the non-Gospel Greek scriptures?

After the Gospels, the Greek scriptures contain many instances of application, clarification, and detail about Christian doctrine. For instance: - The *Book of Revelation* certainly gives many specifics about the end times, as revealed by Jesus to John in a vision. - In *Acts*, Peter was shown by God that he "*should not call any man common or unclean*". But these are not newly introduced doctrines or concepts: - Jesus talked about the Tribulation and about the Kingdom of God, and the latter prophets talked about the resurrection of the dead and the day of the Lord. - Jesus told the disciples to "*teach all nations, baptizing them*". Do the rest of the Greek scriptures contain *any* totally new Christian doctrines not already mentioned in the Gospels or Hebrew scriptures?