I have a friend who says that over the centuries the organized church suppressed what Jesus taught, and that what we have in our Bibles today isn't the full story about Jesus (or even the right story). I don't know where he gets this, but is there any truth to it?
No, there is no truth to this. Recently, some popular novels have claimed this, but they have no basis in fact, and they should be taken only for what they are: fiction.
It is true that during the first few centuries after Christ some pagan philosophers tried to blend Christianity with their pagan beliefs—but Christians strongly rejected their efforts. Interestingly, the Roman officials who persecuted the early Christians understood the difference between Christianity and these pagan beliefs; those philosophers were never persecuted, while Christians were.
Never forget: Christ alone was God in human form, and He alone is the divine Saviour sent into the world to save us from our sins. The Bible says, “For in Christ all the fullness of the Deity lives in bodily form” (Colossians 2:9). Because of this, He cannot be made part of any philosophy or system that denies His uniqueness. Jesus declared, “I am the way and the truth and the life. No one comes to the Father except through me” (John 14:6). The proof of this is that He rose again from the dead.
The real issue, however, is this: What does Jesus Christ mean to you? Have you faced your own need for God’s forgiveness, and are you trusting Christ alone for your salvation? Don’t turn away from Him, but by faith commit your life to Him today.