Simple really. Preachers are the ruiners. They take away people free will by infecting them with the blasphemy they call religion. The you Trent refers to is the Church itself. To the logical mind, the size and strength of the Church and the ignorance of its followers is overwhelming. Later in life (when a person has awakened), he realizes that he has been duped. Finally, able to see the truth, the enlightened individual knows the Church has no real power and he can enlighten others leaving the Church powerless to stop him.
Very powerful song. I just wish people of the Church who know they are lying to their cattle would grow the balls to tell the truth rather than continuing to serve their s*t.