I have always assumed in a free society that any person or group of persons was free to buy or not buy products based on any reason or reasons they can come up with. I have also always assumed that members of our society were free to join with others to attempt to influence the behavior of corporations through group boycotts or other tactics ( I seem to recall sitting through shareholder meetings in which a shareholder - I think he was a minister, in fact, would raise issues concerning the company's affirmative action plan).
In fact, I seem to recall various announced boycotts of say, grapes or companies doing business with South Africa (in its apartheid days). Some of these boycotts were even justified on religious grounds.
More recently, I have seen the World Wide Council of Churches call for economic boycotting of Israel (at least I assume that's what is being referred to here:
This week the World Council of Churches (WCC) joined an ever expanding movement across the Christian World and condemned the “illegal” Israeli occupation of the West Bank and Gaza while highlighting plans to apply “economic pressure” on Israel.I have not, ever heard the term "religious fascism" applied to any of these boycott efforts. Nor have I seen any condemnation from the "left" of such efforts as constituting religious interference with political or economic matters.
So the left cannot be opposed to religious involvement in matters of conscience per se. What they mostly seem to be opposed to is "conservative" religious forces adopting the tactics of the left and applying them successfully to what the conservatives view as matters of conscience.