I'd tell him that he's the reason for the weak minded, overly zealous idiots who constantly use religion as a crutch. I'd also let him know that I was much more content in my ignorance.
I have read the book of Job and yeah the devil had to have permission from God to do what he did but if you would really look at it it was a test for job to see if he would still worship God. I will will add that he did choose to worship God no matter what he was going through.