Preachy pop can be awful, even boring (rock’s greatest sin). Yet Steve Earle , the Schertz-raised rocker whose work has grown exponentially more political, has avoided these traps. Earle might be typecast as a musical Michael Moore, but “Rich Man’s War,” from his latest, The Revolution Starts…Now (Artemis), is an evocative work whose message doesn’t need to beat you over the head. Likewise with “Home to Houston,” which turns an American soldier’s plight in Iraq into a truck driving song. Earle’s so innately talented he could sing the Patriot Act. So if he occasionally strays, as he does on the tedious “Warrior,” it’s easy to overlook. He doesn’t take himself too seriously, either. “Condi, Condi,” a love song to our National Security Advisor, features him as straight man (“People say you’re cold but I think you’re hot”). And “F the CC” is a near-perfect bonehead rock anthem. “A democracy doesn’t work that way,” Earle intones. “I can say anything I want to say.” The unprintable chorus that follows does not disappoint.