Another of my favorites.
Carl Sagan said: "" You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep-seated need to believe.""
All you can do is sow seeds of doubt, indirectly, and hope they take root. When someone believes but actually cares about truth, rather than paying lip service, there's a real shot. But it will never be an overnight shift in thinking. These things take months, if not years.
The need is strong for some of them. Its hope that something out there is going to listen and answer them and make it better. Its a parent child relationship. I was there long ago.