[jennyp]

It is quite possible that other intelligent beings exist and that we will never find them.

Hmm... Atheists might be troubled by that juxtaposition (intelligence and non-discovery).

Not really. An intelligence that we will never find (nor evidence that this intelligence ever did exist) would be, in practice, the same as an intelligence that didn't exist in fact. Such an intelligence may still be compatible with Deism, but that's as far as a theist could take it.

[AndrewC]

An intelligence that we will never find (nor evidence that this intelligence ever did exist) would be, in practice, the same as an intelligence that didn't exist in fact

I think there's this cat that a lot of people argue over that would fall into your definition.