blind faith
belief without true understanding, perception, or discrimination (http://www.dictionary.com/browse/blind-faith)
Believer I don't think my father accepted the 'truth' without true understanding. When he accepted it he accepted it skeptically at first, but he was as sure as he could be that it was correct with the true understanding of the good news regarding 1914. I think that suggesting that it was blind faith gives the impression that people like him gave little thought to it.