So you saying that it would be acceptable if individual members say were in a prayer march over abortion, but if the pastor came and announced that his church was part of the march, would be wrong?
No, not a prayer march. But there would be some situations where some level of partnership would be unavoidable...politics, for example.
isn't the seperation to be done along line of doctrines , NOT social issues that different churches can agree on are wrong?
You are making an imaginary separation that isn't there. "Social issues" ARE doctrinal. I also think you misunderstand; I have no problem with other believers. I have a problem partnering w/ catholics, mormons, and others who are not actually in the Christian faith. You can partner w/ Presbyterians or Non-denoms all day long...