I think socialists in the United States have to easily and comfortably come down on the side of religious liberty. In fact, ahead of the curve, be in favor of unpopular minorities such as Mormons and Jehovah Witnesses having the same rights as everyone else. This will establish your street cred as it were.
And then do the mainstream stuff. Be in favor of the rights of Catholics in parts of the country where they're minority, and the rights of Protestants where they're a minority.
Can you point out any examples of them typically doing the opposite? It has always been my impression that Leftists aren't afraid of particular sects. One of FDRs liberal reformers of the Federal Reserve system was from Utah. Jehovah's Witnesses of course hold it is unGodly to participate in secular government at all.
As a general rule the American Left has in fact been widely tolerant of religious background.
Perhaps you mean they should silence atheists and Darwinists and so forth among themselves so as not to step on sensitive doctrinal toes. The flip side of liberal tolerance is, indifference to such doctrines and leaving the religious to sort out how they handle the modern world for themselves--as far as
religion goes. Religion is their problem. But as far as being a citizen who aspires to rights and dignity and power, the American Left has a long tradition of being a tent anyone can join.
Are American leftists more anti-Semitic than other Americans? Funny how many Jews one meets in those circles--it is in fact a tenent of the Right that leftists are suspicious characters for having Jews among them. Catholics? Loads of liberal and progressive Catholics--if the Church tries to turn that around by its anti-feminist policies, well, that's a major reason so many of us raised in that tradition have dropped out of it. But lots of pretty progressive people keep going to Mass and having their children baptized anyway.
Senator Harry Reid alas is no socialist, I'm afraid. But his biography claims strong working class ties, and guess what religion he is. In Nevada, Church of Latter-Day Saints is always a good guess. Again the LDC church hierarchy like the Roman Catholic is actively against the Left, yet a fair number of its faithful wind up progressive anyway. And back in the day, in the 1840s, I don't think it was leftist progressive Americans who persecuted them in Illinois. And if it was, the Mormons made their peace by the Depression as I've said.
Actually quite a few steps in American progress were made with the help of religious groups who were on the outs at the time--Baptists, Methodists, etc. I don't think the American Left, not as I've found it, is generally bigoted against unusual religions--that is and always has been a preferred stance of the Right, that "some people" are just beyond the pale and should be hounded out, or anyway subordinated.
So whence comes this implication that American Leftists have in fact led in bigotry?
It seems very alternate reality to me!
It seems to me that American leftists have always been appropriately tolerant. Any program on their part to be more on their side would be to go beyond the terms you suggest they fall short of. In fact the American leftist tradition always did and does champion the rights of odd minorities to have the same rights as other people more than the right ever has. This is not to say that they haven't fallen short--one way to tell a socialist from a communist in the 1920s and 30s was that the latter talked about equal rights for African-Americans while most people choosing the label socialist kept quiet about it. But socialists were not more racist than conservatives in those days, some quietly or loudly out of step demonstrated being less so.
Show me a socialist campaigning on keeping out the Mormons, or the Baptists, or the Jews, or the Catholics. I'd be surprised if you can and still more astonished if the conservatives of that time and place were more welcoming of them. For a socialist not to be for equal rights for all is to betray his own program and professed beliefs.
Now if by "having the same rights as everyone else" you really mean something else, like "the pronouncements of their religious leaders should be enacted in civil law because to do less is to disrespect them," then clearly we've crossed a line beyond tolerance, acceptance and even welcoming, all of which I expect of anyone calling themselves a socialist in any meaningful sense, into submission to doctrinaire religious leaders who may not even be representative of the actual practices and beliefs of their own professed followers, let alone the community at large. If this be disrespect, I can only apologize for hurt feelings, but if the community as a whole does not judge that this or that doctrine should be law, it is up to the believers to practice it out of duty and faith and let the heathen go to hell in their own way, if that is where they are headed. They may persuade, they cannot dictate--because one church's doctrine is another's sacrilege.
In this context, and this one only, the one where some faith group claims to have the sole truth and that all others must bow before it because God wills it, this is where socialists and other leftists do defy churches--be they little minorities or be they the dominant faith of a region or country. And only by accepting the narrative of the American Right nowadays, that people who defy conservative pastors are sinners and thus unworthy of citizenship and should give way to theocrats, can I place your implication of socialists who don't care about the rights of religious minorities in any context at all. But even then it is senseless--it is religious majorities, or those who claim that mantle anyway, that leftists defy. When some group is in a minority and far from demanding its doctrines become law, their friends are the leftists, not the conservatives.
We haven't had very many generations where an organized party that calls itself socialist has had any serious footprint in American politics anyway, so I have to wonder where you might dredge up an example of one of these anti-Mormon or anti-Catholic or Jehovah's Witness-bashing American socialists from anyway. Did Eugene Debs ever do that? Norman Thomas, the minister? Bernie Sanders? Who the heck on the Left are you saying has actually done this, and honestly can you not yourself think of more examples of those who have done exactly as you recommend?
It evidently did not propel them to power. I would never say though they should have done otherwise as a road to power, any more than the fact that I breathe oxygen and yet am in a rather sad place in the world suggests to me that I should cease breathing oxygen and go start breathing chlorine instead. For a rightist, tolerance and respect for diversity, especially anyone who is in a weak position in society and needs a friend, might be optional I guess, but one cannot be any kind of progressive and not understand this is essential, necessary if perhaps not sufficient.
Either explain what you mean that I misunderstood, or else look elsewhere.