Either Benedict hopes that meeting the cultural luminaries under Michelangelo's frescoes will inspire them to start tackling issues of faith with greater fervor, or he'll have a team of evil monks descend from the ceiling to wipe-out all the artsy atheists.
The latter outcome notwithstanding, there's something appealing in the idea of putting religion back on the artistic agenda, especially after a decade of the art world being totally devoted to the mystical powers of the market. Additionally, religion is a pretty dear subject to most people's hearts (and souls, I guess), so it could help with the never-ending push to get more people engaged with contemporary art. The full list of invited artists hasn't been released yet, but it includes Bono (which, ugh), architect Daniel Libeskind, composer Ennio Morricone and theater director Robert Wilson. Already, artist Bill Viola has turned down the invitation, presumably anticipating the ambush.
Update: Per Artnet, Bill Viola has decided to attend the Pope's art party after all.