"WITH "THE HOLY TERRORIST," playwright Howard Roman succeeds in one of the most difficult of theatrical ventures -- the historical play.

In this fierce and physical treatment at Source Theater's Warehouse Rep, Roman sketches abolitionist John Brown as a self- styled avenging angel who believes his rebellious acts of violence are ordered by God. Roman creates believable, multi-dimensional characters, with an evenhanded handling of Brown's contradictory nature, and provides the necessary exposition and background without becoming dry or didactic.

The production is further enhanced by a clever piece of casting. Source founder/ director Bart Whiteman is John Brown -- a man with a holy mission, embattled, self- righteous, paternal, inspired and slightly mad. As an actor, Whiteman has undeniable presence and strength onstage.

Under Robert McNamara's energetic direction, scenes shift neatly back and forth in time and place, making some telling juxtapositions: Now Brown and his band are roughing up a terrified pro-slavery family; now Whiteman turns slightly and Brown is eloquently wooing unwitting Boston stuffed- shirts into backing his humanist cause. And in one particularly vivid moment, a man rolls from the raging battle at Harpers Ferry in which he was wounded, back into his prison cell, where he lies feverishly envisioning the scene.

McNamara uses live musicians to good effect. Three percussionists -- on congas and snares, plus beer bottles, jew's harp and other folksy instruments -- send a pulse through the house, heightening the tension.

As usual with Source, the quality of acting in the large ensemble varies, even within individual performances. There is a panoply of conflicting accents, and several actors confuse volume with passion But there is also much vigor and conviction.

THE HOLY TERRORIST -- At Source Theater Warehouse Rep through June 29.