How could one (and should one) convert someone from pseudoscience?

I’ve known for a long time that some peo­ple who are very close to me are some­what in­clined to be­lieve the pseu­do­science world, but it always seemed pretty be­nign. In their ev­ery­day lives they’re pretty nor­mal peo­ple and don’t do any crazy things, so this was a topic I mostly avoided and left it at that. After all—they seemed to find psy­cholog­i­cal value in it. A sense of con­trol over their own lives, a sense of pur­pose, etc.

Re­cently I found out how­ever that at least one of them se­ri­ously be­lieves Bruce Lip­ton, who in essence preaches that happy thoughts cure can­cer. Now I’m start­ing to get wor­ried...

Thus I’m won­der­ing—what can I do about it? This is in essence a re­li­gious ques­tion. They be­lieve this stuff with just anec­do­tal proof. How do I dis­prove it with­out sound­ing like “Your re­li­gion is wrong, con­vert to my re­li­gion, it’s right”? Pseu­do­scien­tists are pretty good at weav­ing a web of lies that sound quite log­i­cal and true.

The one thing I’ve come up with is to some­how in­tro­duce them to clas­si­cal log­i­cal fal­la­cies. That at least doesn’t di­rectly con­flict with their be­liefs. But be­yond that I have no idea.

And per­haps more im­por­tant is the ques­tion—should I do any­thing about it? The pseu­do­scien­tific world is a rosy one. You’re in con­trol of your life and your body, you con­trol ran­dom events, and most im­por­tantly—if you do ev­ery­thing right, it’ll all be OK. Even if I suc­ceed in crush­ing that illu­sion, I have noth­ing to put in its place. I’m wor­ried that re­veal­ing just how truly bleak the re­al­ity is might dev­as­tate them. They seem to be draw­ing a lot of their hap­piness from these pseu­do­scien­tific be­liefs, ei­ther di­rectly or in­di­rectly.

And any­way, more likely that I won’t suc­ceed but just ruin my (healthy) re­la­tion­ship with them. Maybe it’s best just not to in­terfere at all? Even if they end up hurt­ing them­selves, well… it was their choice. Of course, that also means that I’ll be stand­ing idly by and al­low­ing bul­lshit to prop­a­gate, which is kinda not a very good thing. How­ever right now they are not very pushy about their be­liefs, and only talk about them if the topic comes up nat­u­rally, so I guess it’s not that bad.

Any thoughts?