Taking God out of it for a min, you don't believe there are concepts or ideas or beliefs that we don't have words for?It does not. All the terms we would use to describe, say in my example, an alien life form could be used to describe "him/her/it/us".
The "god is so mysterious we can't even conceptualize something different than ourselves because our language only has words to describe humans" is just a weak excuse.
The English language is the most versatile of conversational tools, concepts inhuman/human/godhood, all can exist and be described in myriad form. Saying it is too difficult is just a weak cop-out.