Unfounded belief in God
I've been debating (In a pub, where all of life's problems are solved) with a friend of mine, who's planning on becoming a priest after he finishes university, on his justification for believing in a god. He admitted that he had no proof for the existence of a god that isn't anecdotal, but that since we can't know anything absolutely for certain other than that thoughts exist, my belief in the existence of a universe is just as unfounded as his belief in a god, that they were both equally valid theories.
I'm a mere Mathematics student, so I'm not that well versed in philosophical arguments and I was unable to counter him, but something about his point dosn't sit right with me. I was wondering if any of you had counter arguments, or wether his point was valid.