The decisional regeneration error stems from the teachings of Charles Grandison Finney.
He taught that salvation was achieved no differently than choosing which career to follow. I've heard preachers teach similar things, not aware their teachings were influenced from hand me down Finney errors. They would teach faith is like when you sit in an chair, or cross a bridge. Nope. That's normal carnal trust, faith is a supernatural gift of God.
Many Princeton theologians among others lamented his teachings, claiming it made false converts. He also lied his way into ministry.
Note Jude speaks of false teachers "creeping in unawares." That is exactly what he did.
I heard, but am not certain, but hope it's true that Finney repented of his error late in life.