Perhaps we can say that that is the mark of a true believer, they will never stop believing in Him. The worst problem we have these days is people falsely converted, and given false assurance by an inadequate preaching of the gospel. That is the reason for teachings such as mine on John 3. Thanks for the comments
I agree with that. I grew up in a church that constantly preached grace. And when I was about 20 this 70 year old woman stood up and said "I get it now". This woman had been in the church as long as I can remember, and was a hard worker in the church. I think she had been there at least 50 years. She sat through the same sermons I sat through, but somehow it just didn't sink in that it was grace not works. I'm glad it finally got through to her.
If that can happen in a church that constantly preaches grace, how much more does it happen in churches that either through traditions or through fads, or simply unfocused preaching does not dwell on grace.