Seems like Christianity is more of a right-wing force these days
In the United States? Basically none. There are still quite a few “liberal” Protestant churches, but they pretty much stay out of politics entirely. They will do good stuff like help the poor and be accepting of LGBTQ people, but they don’t go beyond that. But nothing that could be called a “movement”. There was this one church in either Atlanta or Detroit, I don’t remember, where they were starting to formulate a very Marxist-sounding doctrine focused on debt forgiveness… but that was literally just one church and they collapsed when there was a scandal among the three pastors that led it involving harassment.
What has helped Christianity endure for 2,000 years is how malleable it is. You can make “Christianity” about anything. Under feudalism it was useful to the nobility for legitimizing their power over the serfs and for keeping the serfs in line. The theological basis for Christianity comes down to what’s in the Bible and what “church tradition” teaches… and those two bases can be made to say whatever you want it to. It’s well known how very little the Bible says about trans people, for example. Or how the only thing the Bible says about abortion is how to perform one. And for people raised in evangelicalism, it’s actually shocking to realize just how little the Bible condemns premarital sex (it basically doesn’t) when it’s such a foundational pillar of growing up in the church. Today in the US, white evangelical Christianity (and really white Catholicism too, now that white catholic minorities like the Irish and Italians have been fully integrated) exist simply to prop up white supremacy and settler colonialism.
So you have this incredibly malleable religion that easily serves power via the base-superstructure relationship. Of course, that means one day Christianity could be a force for good - under communism at least. But as long as we live under a capitalist base Christianity will pretty much only reflect that.
But if you’re interested in trying something yourself, you can try reading up on Karl Barth. IIRC he tried to incorporate dialectics and German philosophy into Christianity. I got into him for a minute before I deconverted, I think there’s stuff there that’s Marxist-friendly, even if that wasn’t Barth’s intention.
What Jesus said and did is mostly pretty dope. The early church was dope to and fully organized around mutual aid. But then it quickly became authoritarian/apostolic. Even in a 'leftist' church the precedent always seems to be respecting authority above all else
I'd be looking at South America, especially with Liberation theology, so that's going to be the FSLN and Sandinismo in Nicaragua as well as in Brazil in particular.
While not exclusively so, Quakers (especially in Europe) are pretty left wing and tend to contain quite a lot of radical anti-war people and environmentalists at the very least.
Aka society of friends. They're pretty okay and have done some cool shit. Can't blame them for Nixon, he's literally the Spiders Georg of Quakers.
Speaking from the US, I've known some Catholic Workers Movement people here and there. There aren't many, but they mean well.
There's a church out in San Francisco called GLIDE that used to be a part of the UMC. They're certainly not revolutionary socialists, but they do some genuinely good work. They have one of the largest soup kitchens in the US, as far as I'm aware. They serve breakfast, lunch, and dinner, and give out literally hundreds of meals a day, every single day. They also do clean needle exchanges and quite a lot of other programs.Only progressive and non - bigoted denomination I know of is United Methodist. The Global Methodist Church is a recently broken off bigot conservative denomination.
That's the closest big group I know of. But there are small radical leftists churches here and there, but they are really fractured and isolated.
The Episcopal Church has been pretty solid on some stuff for a while. I'm not super familiar, but a friend of mine was involved with one in Alabama that was alright. They're a little too liberal to really be called left, but they're cool with queer people and that's like miles ahead of most churches in Alabama
For the us;
I think the catholic workers are still around.
There's also Mothman Ministries down in one of the Virginia's. Reverend Ollie is a cool guy, and worth following. A dad, a trans guy, trying to keep body and soul together and help people around him down in Appalachia.
Not really a movement, but what I've noticed is that within liberal religious traditions that have a bit of a history of social justice and mutual aid, the younger generations (who are mostly not active churchgoers at this point) have taken very kindly to radical literature and ideas.
Universalists seem chill but I don't hear about them doing big moves. Like, I have been to meetings of cool groups in their space, which is nice. Back when it was a thing I went to a few secular humanist meetings there. It was a funny juxtaposition
