One of the main sources of barnacles laid over the life and teaching of Jesus are the ideas of Augustine of Hippo in the 3rd and 4th centuries. Let's consider just 3 of his additions today.
First and foremost was his idea of original sin, that is his interpretation of the ancient myth of Adam and Eve and the eating of the forbidden fruit. He declared that this story was about sin and how from then inward all humans were born as sinners and were lower than the low. This was a new idea. It was not the Jewish interpretation (and it is their story), so Jesus never heard it. Tentacles of this ugly interpretation spread throughout the Western world. People whipped themselves, wore vests of nails, mistreated themselves, others, animals and earth because creation became bad and sinful.
Out of this he created individual salvation. Jesus spoke about bringing the kingdom of heaven to earth, of loving and caring for one another, etc. Augustine spoke of whipping yourself into shape to get into a heavenly next life. The emphasis of what it meant to be a Christian whirled around 180'. And later people took off and ran with it. Luther said we sin in the womb. Calvin spoke of total depravity, etc.
As an aside that is important to half the human race, Augustine agreed with Aristotle. Women, he said, had no souls. The extreme bias against women lingers still. Usually men don't think so, but ask any women about how anti-female bias has shown up in their life. It's better than it has been for centuries certainly, but it lingers.
I don't have time or space to go over in detail all the heart breaking ideas that Augustine planted and others extended and went wild with new and degenerate applications.
Part of the situation is that Augustine's ideas have insinuated themselves into theology for so many centuries. About 200 years ago, with the birth of the scientific method and the Enlightenment, his ideas began to be questioned. Mainstream schools of theology began to teach ideas free of Augustine and his later proponents. But many preachers did not pass it on. Many are stuck in original sin, individual salvation for the next life, women excluded from high places, and other ideas opposite of Jesus' life and teaching.
To restore The Way of Christ and turn the tide around, I propose we need to pull off the teachings that lead us away from Jesus. Will you join me.