Well, the Force isn't why the Death Star had an improbable weakness, even if it's what let Luke time his shot. He was right about what he was saying at the time, and as it happens Vader's religion is bullshit because the Sith are wrong and the Force actively subverts them.

Probably would have been easier to not let them do Force stuff but Lucas (iirc) likened them to parasites/cancer (with an all consuming greed that will kill both the host and then themselves) on a living organism so fair enough. It's not like you can just will a tumor off you.

Tl;Dr they're both wrong because they're fascists, one just likes technology and the other likes space magic