"If you hold to my teachings, you are really my disciples. Then you will know the truth, and the truth will set you free."
- John 8:31-32
The Bible is actually void of most of Jesus' authentic teachings and, among others, it does not tell us what truth was he referring to in this instance. In the verses following John 8:31-32 he explains what he meant but the explanation is now extremely confusing and it sure looks like something inserted there by church scribes or like a text heavily edited in order to divert attention from Jesus' anti-religion message.
As you are going to see in the book, Jesus was, indeed, teaching against religion, and the truth he was referring to was meant to liberate man from the mental trap of belief. When we pay attention to what the text says it is obvious his "Father" was not the all-knowing god of religion, otherwise a composite fictional character. Similar to what we will later have in the case of Muhammad, his teachings included knowledge that was "out of this world," as in of a non-terrestrial origin. This was information he became initiated into between the age of 12 and 30 at centers established thousands of years ago all over the planet. The Bible says though nothing about this eighteen-year period in his life, reason why researchers appropriately describe it as Jesus' missing years.