I absolutely agree with you, and would add, that the teaching of sin as a mistake is basically parallel with the new agers who teach that sin does not exist, and for an overseer to regard sin as an honest mistake, and then for the hearers to believe this is abominable; it is as if the blind lead the blind, and it is exceeding sorrowful to hear such things, which seem to be more and more in the very bosom of many churches.
Moreover, this contamination of corrupt doctrine sets itself in the hearers hearts, and by the time they hear the love of the real Truth in Christ Jesus, they are very reluctant to even hear the Truth, let alone accept it, and even become defensive of their sins, that their sins are not sins, but mere honest mistakes.
The grace of our Lord Jesus Christ be with you.