Name one.
Why?
I mean, sure... given that I have a degree in Philosophy, I'm more than qualified to take any one of his arguments and break down all the logistical problems with it. But this isn't the right forum for it.
More importantly, why should I put forth such effort? You said that McDowell's book should convince me that God is real. I'm telling you that I read it, and it didn't... nor does it have much chance of convincing anyone else who doesn't already accept God's existence on faith alone. How is this my burden to explain why McDowell was entirely uncompelling?
You can go on through life believing that he's a philosophical genius and I'm just too dense to see it... but you won't gain many converts that way.