"The question arises: how did it happen that the church, which in the first centuries of its existence fell into heresy, began to possess such power and influence? How did the simplicity and humility of Christ and his early followers be replaced by pride and luxury?" (Mankind in Search of God. 2006, ch. 11. Apostasy: the path to a dead end. P. 271.)

You see? In these Watchtower texts, "heresy" is portrayed as absolute evil. Your first definition shows the relative nature of this evil. For example, I lost my wallet with money. It's bad for me. And for the one who found this wallet, this is a great joy! I think that if we discuss this "relative" meaning of the word, we will end up getting confused. Let us decide that "heresy" in the context of our discourse is "the work of the flesh," which means that the heretic "shall not inherit the kingdom of God" (Galatians 5:20). Do you agree with me?

28. Galina: Yes, I agree!

29. Me: And how do you distinguish heresy from error? I have acquaintances, former Jehovah's Witnesses, who claim that the most important difference between heresy and error is who expresses this heresy or mistake... If a Jehovah's Witness speaks incorrectly, then it is a mistake, and if a person who does not belong to the OSB speaks incorrectly, then this is heresy. Isn't that right?

30. Galina: No, it's not. Not exactly...

31. Me: Can Jehovah's Witnesses speak heresy?

32. Galina: No, they can't.