It's easier to rationalize something deemed 'magic' as a terror-inducing thing rather than a boon since the thing could dominate in totality. Giant clipper ships, napalm, penicillin... the enemy army has ships from god, fire from black magic (the gods). Their priests are able to revive their fallen (penicillin), etc.
When you and your allies have all the tech, but the enemy still finds cheap and easy ways to make them ineffective (Vietnam War). Makes one question if all the gizmos are worth it, really shakes up the morale.
I was not talking about about a confrontational situation though. Most cults and pseudoscience are just plain scams.
