"It's not a matter of criticizing the people who think in deluded terms. It's questioning the delusion(s) themselves"

IMO, it is a matter of showing respect, rather than disrespecting anothers persons belief. Of course, free speech allows a broad scope to say just about anything one wants, in just about any way. But, as moral and social folks, with a degree of kindness, questioning a belief can be done in a way that respects others and avoids discourse. But, the faceless internet stimulates many folks to "shoot from the hip, (often using unkind language) at others in a way most would never do in a face to face discussion.