[TheReallyBest]

I would hesitate to label promoting a belief in that which is unobservable as "useless":

In politics a noble lie is a myth or untruth, often, but not invariably, of a religious nature, knowingly told by an elite to maintain social harmony. The noble lie is a concept originated by Plato as described in the Republic. More here: http://en.wikipedia.org/wiki/Noble_lie

Please don't misunderstand the "lie" part as being an attack. It's just the example I was familiar with.