The appeal to consequences (if we evolved/there's no god, then my life has no meaning) seems to be pretty effective at keeping people stuck in silly belief systems, or driving them further in when they feel threatened.
The other day I was bored at the KH and skimmed through the KM. There was a sample presentation for one of the brochures on how life began or whatever and the presentation essentially followed this formula. Ask what the HH believes, read a quote about how empty life is for evolutionists and then explain to them that if they'll believe in fairy tales in the face of all evidence they can be happier.