Likewise, we’ve been rewatching the MCU over the last month or so. We wanted to be able to watch WandaVision and Falcon in and the Winter Soldier in context.
Personally, I think the MCU films have a lot for thoughtful reflection around themes like power and responsibility, the nature of evil, the value of life, friendship, love, many ethical issues, and, of course, sacrifice.
As a life long lover of Sci-Fi/Fantasy, I have come up against various views over the year. Some reaching utter fever-pitched hysteria at the launch of the Harry Potter books/films.
Eventually, though, I have come to see that whether Christian’s should watch this, that, or the other, largely comes down to conscience. And as such, I try to deploy the same approach Paul advocates in Romans 14.
Some can watch almost anything and find edification in it. And that fine.* Others cannot. I do not pass judgement on those who prefer not to watch Sci-Fi and likewise, I hope that they do not judge me for my love of it. Similarly, if I know a particular person takes issue with these types of films/books/games, etc., then I make a concerted effort not to talk about it around them. The reason being that I do not want to put a stumbling block in their way.
*Obviously, there are exceptions to this general principles. Eg. Pornography.