Did you ask him what's the point of God testing us if he is "All-knowing"?
didn't get that far, kind of backed off to be honest, I could see through a whole pile of their arguments from the get go but didn't want to blow my cover or make things awkward so early on in my 'new life'.
We've lost touch since, I still rate them as a decent human being, in fact much as they'd hate me to say it, I consider this person to be too good for Islam.