Lambert, Green Photo by Craig Schwartz

Religion is one of the subjects most of us were warned not to discuss among family or friends. Mary and Margaret O'Brien, sisters and housemates, and their parish priest, Father Murphy, ignored that warning. The tumultuous, yet hilarious, results of that failure to heed conventional wisdom are manifest in Evan Smith's provocative play, The Savannah Disputation, on The Old Globe Theatre's Arena Stage.

In all fairness, it was Melissa, a door-to-door missionary, that catalyzed the "disputation" in the present-day Savannah household. Turned away by the irascible Mary, but soon after welcomed inside by her sweet-tempered sister, Melissa succeeds in planting doubts where an unexamined faith in Margaret's Catholic religion once stood. To teach Margaret a lesson in creedal stoicism and to embarrass the evangelical preacher, Mary invites Father Murphy, her unsuspecting priest, to dinner, hoping a religious idea contest will prove Melissa an empty-headed heretic and her priest a learned and loyal Catholic hero. When Melissa arrives with her box of Biblical tricks, the showdown begins.

Before it ends, each of the characters will have examined much more than the Good Book and its history, and at least one of them will eat a hefty slice of humble pie.

The sisters' modest home is brought to realistic life by Deb O's cluttered, old-fashioned set in the round, offering a bird's eye view of the entire interior. Because the actors are always visible, even when in different "rooms," the action and arguments that rise and ebb under Kim Rubinstein's elegant direction are always visible and immediate. The cast is more than up to the challenge. Mikel Sarah Lambert gives the slightly batty, but very lovable, Margaret an Edith Bunker persona that plays beautifully opposite Nancy Robinette's mean-spirited but very lonely and conflicted Mary. James Sutorius manages Father Murphy's kindness and his outrage with equally convincing aplomb. Kimberly Parker Green as the smart, but self-doubting Melissa is just splendid, with excellent timing and facial expressions that instantly communicate her thoughts.

Having such a high-caliber cast is critical to this production, because this is a very entertaining, very funny play about very serious subjects.

This is a play about loneliness and loyalty as much as it is about dogma and doctrine. Couched in the intelligent script is the idea that doubt is a universal human trait. As the sisters, their spiritual advisor, and their disquieting messenger of God discover, misgivings can stem from crises of faith, family, and friendship. Doubts can burst into one's consciousness in unexpected and unwelcome ways. Once acknowledged, those uncertainties can power a life change.

This play is not about criticizing a particular religion as much as it is about poking intellectual and clever fun at unexamined religious dogma. Judging from the spontaneous audience applause during Mary and Melissa's match of wits and Biblical wisdom, it succeeds in making the points personal. And that is what we were all warned about in the first place.

The Savannah Disputation by Evan Smith plays through November 1 on the Old globe Theatre's Arena Stage at the San Diego Museum of Art's James S. Copley Auditorium. Performances are Tues-Weds and Sun at 7pm; Thurs, Fri & Sat at 8pm; Sun matinees at 2pm. Tickets are $29-$62, with discounts for students, youth, seniors and groups.