The vicar told a joke.
A joke. In church.
I don't think it's even an idea so much as a basic human need/instinct. There's a reason why no human society in history ever has developed without a spiritual element. Indeed, I would go so far as to say that, as a species, we naturally, unconsciously believe in God (or some variation thereof), but have to work to use our rational mind to consciously suppress that belief.
You conflate spirituality with God, but the two need not have anything to do with each other whatsoever.
So when you say "or some variation thereof" what you actually mean is something entirely different to God (specifically, an acceptance that there is much about the world - and in particular human consciousness - that we do not yet understand). There is no reason at all - other than intellectual laziness - for this ignorance to manifest in a belief in God.