you're one of those lazy bastards who just deny the existance of morality altogether, this thread is not for you. Morality does exist in some shape or form, that much is undeniable.

I am not sure if this is lazy. There are plenty of moral error theorists out there who write books and articles about why morality is false and provide solid philosophical arguments for doing so (e.g. Jonas Olson, Richard Garner, Richard Joyce). It is true that they criticize a specific form of morality—moral realism—but they do so because they consider every other form of "morality" to (1) ignore how morality is commonly understood, i.e. inescapable, absolute and normatively irreducible; to (2) be a slippery slope towards absolute moral judgements even if the common understanding of morality changes. (2) takes shape in the form of different arguments. One of these is that moral language itself lends to absolute moral beliefs; another is that the historical baggage is not so easy to get rid of. These are absolutely valid concerns and are in no way "lazy".

Before A is brainwashed, B's actions appear to be evil, because B is acting against A's interests, but after A has been brainwashed, B's actions actually helped A reach the new life goal of jumping off a plane, which would seem to imply that B's actions were good. So what the fuck is going on here?

Certain moral skeptics have also recommended the above revisionism of morality. For instance, Joshua D. Greene proposed to redefine "moral" to mean "concerned with the interests of others." Error theorists and some other moral skeptics are skeptical of this because of the aforementioned reasons. Greene even tried this indirectly in his book Moral Tribes, and if I remember correctly, many of the reviews that I have read seemed confused by his arguments as a result. The difficulty of trying to change the meaning of morality seems tremendously difficult as a result.

Besides, I would say that even if we were to make a revision of morality that it isn't desirable to talk about 'good' and 'evil'. 'Good' and 'bad' would suffice, but to invoke the word evil definitely brings a sense of absolutist overtones. We can however already use the words 'good' and 'bad' without invoking morality, using neutral word combinations like "a bad friend", "a bad neighbour" and so on, which would rather describe a bad function in the very much same way of saying that a car is bad. In this sense, morality and moral language are not all the tools we need to show our disapproval of a person's actions.