Good vs. evil is a staple of comic book stories, but the DCEU films have slowly been developing a unified theme that takes a more nuanced look at this old dichotomy that only now, with the release of Wonder Woman, is starting to become explicit.

It’s surprising given how unsubtle the handling of religious metaphors was in the first two films. Wonder Woman is that piece of the puzzle that makes the overall image discernible.

In Man of Steel, Superman is a reluctant savior who, during his hitchhiking, soul-searching years, is given every opportunity to get back at human petulance with an overwhelming vengeance that no one could oppose, but instead chooses to do good. In the end, he kills the guy with the Obvious Goatee of Evil (i.e. a god kills a devil), but makes the murder okay by feeling very bad about it. A thought to hold: Jor-El’s belief that everyone has the potential for good.

In Batman v Superman, Lex Luthor believes Superman is living proof that omnipotence and omnibenevolence are incompatible (a heavily discussed topic in real-world theology), so he stages a practical demonstration of his point: under the right circumstances, Superman may as easily be a god as a devil, and Luthor repeatedly calls him by both names. The crowd of skull-painted faces worshiping Superman in Mexico makes this ambiguity explicit. (At other moments in the film, Batman and Doomsday are also referred to as devils.)

In the end, the god sacrifices himself to kill a devil. A thought to hold: Batman’s belief that no one stays good in Gotham, followed by Superman’s belief that no one stays good in this world, followed by Wonder Woman’s belief that humans have built a world with no place for goodness, followed by Batman’s newfound belief that humans do mess up but are still good.

In Suicide Squad, Amanda Waller is worried that the next Superman might not be good, and her solution is to recruit the help of evil. Her team includes a reluctant villain, a man literally called the devil (El Diablo), who sacrifices himself to kill a self-professed god. A thought to hold: Waller’s belief that even the worst of bad people can do good.

In Wonder Woman, evil is initially explained in the most simplistic and naïve of terms as the supernatural influence of a being who has corrupted humankind’s otherwise good nature (which many real-world people actually believe to be the case). Interestingly, Diana does not abandon this belief after killing the real Ares, but after killing a regular human she believed to be Ares.

This has a doubly powerful effect: she has to come to terms with how complicated real human nature is (here, Steve Trevor’s plead, that saving humans can be the right choice even if we don’t deserve it, is priceless), but she also has to find a better reason to kill Ares, now that she knows even his death won’t cure the world. A god kills a god, and still the job is not done. A thought to hold: Ares is a god, but plays the role of the devil. He killed the other gods, and Diana is the last one. Our world was already forsaken long before there were superheroes to defend it.

This gives added weight to one line spoken by Diana in the Justice League trailer: she had spent her life believing the age of heroes would never come again. The League is her beloved pantheon restored (a point already made in stories like the animated Justice League: War). And guess who’s the larger-scope villain waiting at the end of the DCEU? Darkseid, a member of an alien race called… the New Gods.

So what’s the big point being laboriously made across all these films? I guess it’s this: no one is good or evil, but you can do good or evil. In real life it’s the first thing you learn as you grow up (or quit religion), but in the world of comic books it’s a harder case to make. Scattered examples converge around this unifying idea: in Man of Steel, Superman takes the role of Jesus, but his victory is not pure. In Batman v Superman, Lex Luthor wants to defend humanity, but discards his own.

In Suicide Squad, Killer Croc’s appearance doesn’t make him a born monster, but the hatred of others did turn him into one. In Wonder Woman, General Ludendorff is not superhumanly evil, only humanly so, and no less terrible for that. Anyone can call themselves a god, and still that doesn’t tell you anything about their goodness. The only assurance left is that it’s good to do good, even if the world doesn’t seem to want to let you, or if you already know it will only solve a very small part of what’s wrong with it.

In order to come to these realizations, the characters of the DCEU each have to renounce comforting delusions. In Man of Steel, Zod tempts Superman, just like Satan tempted Jesus, with a vision of a world under his iron fist. In Batman v Superman, Batman only grows as a hero when he discovers he was wrong to believe Superman didn’t have a human side.

In Suicide Squad, it’s El Diablo who first shakes off the illusion cast by the Enchantress when he stops yearning for a world where he can pretend his mistakes didn’t happen. In Wonder Woman, Ares copies Zod’s trick and shows Diana an apparently perfect world that she admits can’t really happen. The shared lesson: there is no paradise. The world is never going to be neatly divided along sharp moral lines, and it’s okay that way.

This is why it was a smart creative choice to change Diana’s origin story from the Second World War to the First one: if you want to show how killing your villain doesn’t automatically fix the world, you can’t do it when your big bad is Hitler, the ethical equivalent of a black hole where all complex things are flattened. Hitler is just too easy, like Voldemort or the Daleks. He is an extreme anomaly in a world that 99.9% of the time is not categorizable in clear good/evil terms. Killing Hitler is the obvious thing to do, which is why we don’t get any moral lessons from it.

And still Wonder Woman managed to carry one of the lessons we did learn from Hitler, namely Hannah Arendt’s observation that the atrocities of war are not committed by monsters, but by normal humans thrown into the wrong circumstances, and that’s the horror of it. The First World War was the time when humankind finally learned how awful and disgusting and pointless war is, and the fault for all of its evils is ours, not the devil’s.

We are all potential gods and devils, and even Diana is nearly pushed to the edge when given the chance to kill Doctor Poison. Up to that point she’s not yet a heroine. Guiding a team across the battlefield and saving a town of civilians doesn’t count: none of those battles is a serious threat for her. Only after being disabused of lifelong lies, deprived of hope, and heartbroken, she finds that she doesn’t need to let such awful circumstances define her.

She is at her most vulnerable precisely when Doctor Poison is within striking distance, and instead of following her mission plan, like any unthinking soldier would, she chooses to be better than her enemy, and only then becomes a heroine.

And then she fries Ares with lightning because of course that’s what you do.