MISS WITHERSPOON: If Christopher Durang is issuing an impassioned rallying cry here, he’s unlikely to be heard over the laughter.

If you’ve ever wondered what would happen if you took Comparative Religion and crack cocaine simultaneously, the answer may be Christopher Durang’s delirious post-mortem fantasy Miss Witherspoon (at the Lyric Stage Company of Boston through April 21). The protagonist of this witty 2005 fable, who’s named Veronica but dubbed Miss Witherspoon by the keepers of Purgatory because she reminds them of “some negative Englishwoman in an Agatha Christie book,” commits suicide in the 1990s, having suffered from depression, bad relationships, and a “disproportionate” reaction to Skylab, the falling space station that threatened to rain tons of detritus upon us. Once dead, she wishes to stick to it. A lapsed Christian perusing her Elysian options, she would prefer “Jewish heaven,” a state likened to general anesthesia and apparently available to all non-believers in an afterlife. Unfortunately, Miss Witherspoon has landed in a Tibetan Buddhist version of Purgatory called the bardo, where the brass — personified by a pleasant Indian woman in a sari — wants to send you back and back and back, like soldiers to Iraq. And that’s not a farfetched simile since this screwball metaphysical and apocalyptic farce is indeed about our troubled world, the religion-fueled conflicts in the Middle East and impending climate catastrophe at the forefront.

But Durang is neither David Hare scrutinizing contemporary politics nor Al Gore with his pointer. His is a crazy, absurdist sensibility steeped in a Catholic upbringing and a charcoal-colored world view. Like Miss Witherspoon, he can appreciate the horror of being sentenced to life, not to mention multiple lives. But the writer’s mind is a magnet for all things pop-cultural, so his loopy protest against earthly cruelty and intolerance incorporates not just the Tibetan Book of the Dead and Jesus Christ in the form of a saucy black woman but also The Lord of the Rings and My Fair Lady — all blenderized for maximum silliness and surprise. And at the Lyric, Durang’s three-ring circus of joke and philosophy is being given a sharply executed, tongue-in-cheek staging with the superb Paula Plum as exasperated ringmaster. Scott Edmiston is at the helm, but some of the effects (which include a Plum Barbie reluctantly descending back toward Earth from an ozone peopled by floating babies), not to mention the deadpan presence of Larry Coen, bring to mind Ryan Landry.

Like most works by the author of The Marriage of Bette and Boo and Betty’s Summer Vacation, Miss Witherspoon is arbitrary and whimsical almost to a fault; this undermines its message and its poignancy if not its amusement value. And it has an oddly optimistic ending, given Durang’s merrily mordant musings on the scariness of the world. “If you can’t fix it, laugh at it and hope to be well out of it,” he seems to be saying — until an unlikely coalition with Miss Witherspoon as its pint-sized center sets out to fix it after all. But if Durang is really issuing an impassioned rallying cry, he’s unlikely to be heard over the laughter as his heroine endures at least one hilariously horrifying childhood among drug-addicted trailer trash and commits at least one ingenious suicide (among several) before acknowledging that perhaps she could change the world if only she could stand it.

Some of Durang’s demands, including Miss Witherspoon’s multiple returns to grumpy infancy, are tricky, and they’re well handled at the Lyric, where the spiritual cartoon is colored within the lines but much is made of the play’s cataclysmic spectacle, particularly in Dewey Dellay’s drolly dramatic sound design. Plum’s reincarnation-buffeted Miss W. addresses the eternal verities with apt perplexity and sarcasm and can gurgle with the best of babies and wag her posterior with the canine elite. Coen and Marianna Bassham are funny as parents saccharine and sadistic. Mara Bhattacharya is both silky and pushy as the spiritual guide who tut-tuts Miss Witherspoon for her “murky, brown-tweed” karma. And if Jesus were really as cool as Jacqui Parker shaking her booty in a John Travolta suit, I might go back to church.