Hi friend!

For what Marxist instance would be best given your background, well there are only two total, to my knowledge, so you could just try out both and see what you like best! They are Hexbear and Lemmygrad. Lemmygrad is smaller but is more focused on Marxism-Leninism in particular. Hexbear has a ML-ancom and everything in between left unity stance and places great emphasis on making the space safe for people of marginalized groups. Lemmy.ml has many Marxists but is not explicitly commie.

For reading recommendations, this can be a difficult question to answer because there are many important texts in the Marxist tradition and some of them, particularly the foundational ones, are dense and challenging to read. I do strongly recommend reading the core works of Marx and Engels, since they define Marxism and later works are based on them. The order in which to read books really depends on how you prefet to read and learn.

I prefer to read from “the beginning” and already knew the relevant philosophical background so I just read Das Kapital right after The Communist Manifesto. But reading Das Kapital takes a long time. Reading groups dedicate months just to Volume 1. If you prefer a faster introduction and summaries, then I recommend Heinrich’s companion text. Heinrich inserts some of his own opinions, but you can balance these out by reading Marxists critical of Heinrich, like Michael Roberts. If you want an even faster and simpler introduction, you can work backwards by reading short overviews from newer texts and blogs and so on and then make sure to try and tackle Capital later. But remember that the farther from the original works you get, the more likely that you will learn something incorrect about them without being in a position to notice it.

Another strategy is to start with Lenin, particularly his own notes on Hegel and Marx, and proceed to Stalin’s overview of Marxism-Leninism, which includes an overview of Marxism. These are much easier to read than the source texts. All of the works so far will have Portuguese translations.

Regarding tolerance of Catholic faith, both instances will likely not care so long as this does not mean contradicting community standards, e.g. a vocal tradcath would contradict the feminist stances of both instances. Both instances have Christian comms, similar to subreddits. Lemmygrad’s all seem to be inactive, though. Hexbear is, generally speaking, against insufferable New Atheist contrarianism (and so many of its original proponents became reactionary).

Regarding having Latin American context, both instances of course have a good amount of comrades from Latin America. I know that Hexbear has an active Latin America comm.