... on the grounds that he no longer finds theism sufficiently credible to warrant devoting further time to research in that field. You all knew that (if not, go here and here), but now Brian Leiter has started a discussion on the topic at his blog. Here is the link.
For the record, my own sentiments about the value of philosophy of religion, and the current state of the field, are captured perfectly by J.L. Schellenberg's comment in the thread at Prosblogion.
UPDATE: Parsons has since left the following comment in the thread of his original announcement at The Secular Outpost:
Thanks again for the many kind and generous comments. I do certainly agree that those who have the stomach for it should continue to subject theistic apologetics to stringent critique. I would especially like for somebody to debunk stuff like that by Robin Collins and John Leslie in the last issue of Philo.
When I helped found Philo, I expressed my chagrin that there were so very few replies to the theistic philosophy that had proliferated. Since that time the publication of books like Graham Oppy's Arguing About Gods, Jordan Howard Sobel's Logic and Theism and Nicholas Everitt's The Non-Existence of God have supplied the logically rigorous and sophisticated critiques that were sorely needed. To really effectively critique the theistic arguments, you need to know as much modal logic as Plantinga, as much Bayesian confirmation theory as Swinburne, and as much physical cosmology as Craig. I am glad to see that critics who have those qualifications are having their say.
Again, I admire and encourage those who continue the battle against theistic obscurantism, but I have such a sense of ennui and disgust that I am going to be hors de combat. I saw a quote attributed to Nietzsche one time that said "I cannot spend my time swatting flies." Swatting flies is what it feels like I've been doing for some time.