As many as 30,000 people are expected to crowd the National Mall tomorrow, and while the forecast is for rain, don’t expect this bunch to pray for sunny skies—they’re atheists, after all.

MONDAY When it comes to examining the state of contemporary theatre, Robert Brustein has few peers. Expect a stimulating discussion when Brustein comes to the J to offer his viewpoint on how the post-9/11 years have played out on stage — issues he takes on in Millennial Stages: Essays and Reviews 2001—2005. District of Columbia Jewish Community Center, 1529 16th St. NW., at 7:30 p.m. $8. Also, from the McSweeney’s camp of writers come Kevin…