If you've never tasted, smelled, or touched coffee before, and I told you it was cold and sweet, how would you dispute me? In essence, coffee does not exist in your world. Not until you actually went to the cup, touched, smelled and tasted it, at which point you would find out that coffee is hot and bitter. Now coffee exists for you and anyone who tries to tell you that coffee is sweet, you can tell them its not with certainty. Because you've tasted it.
God is the same way. Right now, you don't know what God is. The only sure way to find out is to 'taste' God. Any other explanation is bound to be confusing and distorted by personal bias.
Just a side note: If all you thin exists are things you can see, touch, feel, hear or smell, your worldview is incredibly narrow.