Now I suppose that God is not overly thrilled when we exclude people from church because we don't like the way they dress (or smell, or the color of their skin), but there is a lot of variability in what may be personally annoying to some people, and what is not a matter of choice. One pastor I knew returned from a mission trip to Africa, and was so appreciative to be back "where people smell good." The people in the African bush, it would appear, are too poor to wash their clothes every day and apply expensive deodorants and perfumes to hide the unavoidable consequences of tropical heat without air conditioning. Many churches in Europe have a dress code, where women are expected to dress modestly (no short skirts, no bare shoulders); apparently men's dress is not a problem there, but it was in a California church not too long ago, where men showed up in speedos (I think they all went to the beach after the service). The pastor wanted to preach delicately against the women's skimpy attire, and his wife reminded him that the men were also a problem. They instituted a dress code.
The particular legalism sermon that comes to my mind today berated another church for "preaching another gospel" because they gave a skirt to a woman visitor in slacks and asked her to wear it. Excuse me, but this isn't doctrine, it's just a dress code. Would this particular preacher accept into his congregation a woman stark naked? I don't think so. Does that make his own theology "legalism"? Hardly. It's just a dress code, to prevent offense to the other attendees. He draws the line in a different place than the target of his criticism, but he still draws the same line and for the same reason.
Many years ago I overheard a Lutheran pastor criticizing the Baptists for "preaching salvation by works." The Lutherans, it seems, are saved by faith and faith alone, while the Baptists preach a works-righteousness (the believer must "make a decision" which is clearly something to do, therefore a work). The Baptists, on the other hand teach that the Lutherans are similarly "preaching salvation by works" because they require the infant to be baptized (which is something to do, thus a work), while the Baptists make no such requirement. I almost laughed out loud.
Some zealots even try to demonize other Christians for the celebration of Christmas or (God forbid!) Easter. I might go along with taking some of the commercialism out of Christmas, but Easter? These people have too much idle time on their hands; they should be spending it evangelizing the heathen, not criticizing the believers.
Jesus' disciples found somebody casting out demons in Jesus name, and
the disciples wanted to stop them because these other exorcists were not
among the Twelve. Jesus said "Let them alone. Whoever is not against us
is with us." I often wonder why the preachers don't get the message.