Rather than reveal what Jesus actually said (he could not write), each Gospel reveals the theology of its writer(s).
Probably the closest to the actual teachings of Jesus comes from the document attributed to James, his brother. Although the NT is a compilation of documents by followers of Paul, they included James because of his direct relationship with Jesus and because James was the Jerusalem leader, having taken over from Peter at a very early stage. James was followed by another of Jesus' relatives, Symeon. Paul, of course was completely at loggerheads with the Jerusalem leadership.
This mystical idea of divine illumination (Christ in you, etc), was picked up by the Gnostics. The Paulines did not include any of the Gnostic writings, thereby providing an unbalanced picture of the primitive church. Acts (of the Apostles) is a religious invention created for political purposes. Several other Acts were written, some have survived.
Doug