"Extreme liberals who look at this should be quaking in their boots," declares Pastor Becky Fischer with jovial satisfaction in the riveting documentary "Jesus Camp." Ms. Fischer, an evangelical Christian, helps run Kids on Fire, a summer camp in Devils Lake, N.D., that grooms children to be soldiers in "God's army." A mountainous woman of indefatigable good cheer, Ms. Fischer makes no bones about her expectation that the growing evangelical movement in the United States will one day end the constitutional ban separating church and state. And as the movie explores her highly effective methods of mobilizing God's army, that expectation seems reasonable.