Who can understand his errors? cleanse thou me from secret faults. Psalm 19:12
…While we insist upon it that not every error is fatal, we wish to guard against the misconception, or false conclusion, according to which it is forthwith pronounced indifferent.
Fatal or indifferent are not the only alternatives. No sin in practice is indifferent, yet our hopes were indeed vain, if all were absolutely fatal.
Every sin in doctrine is dangerous, whether fundamental or not.