Think of a congregation that prays for its neighborhood and then organizes a food drive. The prayer didn't magically stock shelves, but it changed people who changed the situation. My opponent keeps saying that's merely the pray-er, as if the pray-er stands outside the situation. But in most real cases, the person praying is part of it: they call, visit, donate, show up. The heart-surgery studies test one narrow mechanism, remote healing, not whether prayer changes anything. A narrower effect is still a real effect. So yes, prayer changes things, often through the people doing it.