There is a way to help a 'perfectionist' see their error - shown them the error with clear irrefutable evidence.
EXAMPLE: 2 Peter 1:16-21
For we did not follow cleverly devised fables when we made known to you the power and coming of our Lord Jesus Christ, but we were eyewitnesses of His majesty. For He received honor and glory from God the Father when the voice came to Him from the Majestic Glory, saying, “This is My beloved Son, in whom I am well pleased.” And we ourselves heard this voice from heaven when we were with Him on the holy mountain.
We also have the word of the prophets as confirmed beyond doubt. And you will do well to pay attention to it, as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts. Above all, you must understand that no prophecy of Scripture comes from one’s own interpretation. For no such prophecy was ever brought forth by the will of man, but men spoke from God as they were carried along by the Holy Spirit.