It is baseless to state certainty.The probability of there being a God is the same as the probability of there being fairies. It is trivial to call myself an agnostic.
If you asked the aboriginal Americans, before the Spaniards landed, if horses existed they'd be wrong to say they didn't, but they certainly didn't have any evidence they existed.
It is silly to say you hold truth when all you hold is a probability. All you wind up holding is your faith.