The simple fact of the matter is that virtually every single human being is bigoted in some way or another AND virtually every one of them is convinced either that they're not bigoted at all or that their bigotry is wholly justified because the people they hate purportedly deserve it.
There's a particular set of bigoted views that's tolerated or even expected throughout most of the mainstream western internet, and according to those views, hating Christans (among others) is at least wholly acceptable, and generally even encouraged. And naturally, the bigots who do it are convinced that they aren't bigots, or at least that their bigotry is justified. And nobody is going to convince them otherwise.
Now, one could get around that, and particularly on the fediverse, by seeking out places that don't reward hating Christians, but unfortunately, those places are almost certainly just going to have a different set of people that everyone hates, and with the way society has divided up, their set is likely going to be even larger and more problematic than the set of people the first place hates.
Really, at least unless and until somebody manages to make a success of a site that actually takes a stand against hate broadly (instead of, as virtually all who claim that actually do just taking a stand against the hate of the groups they support and conveniently ignoring the rest), about the best you can do is settle for a place that's somewhat less noxiously hateful than another, and as necessary, block its worst elements.
And yeah - if you're so inclined, you can try to get the bigots to see the fact that they're bigots, but don't expect any good to come of that.