Joining the Jihad Club: BATKHELA, Pakistan -- Shahid Hussain, a bright and articulate man of 19, carries two plastic identification cards in his vest pocket. One is from a private college where he has studied science part time for the past two years in hopes of becoming a doctor. The other card, of far more recent vintage, is his ticket to a very different fate. Issued Oct. 28 by the Movement for the Implementation of Islamic Law, it certifies that Hussain has vowed to follow the path of "sincerity, virtue, patience and unity," taken a brief training course in physical endurance and target shooting, and registered to fight an Islamic holy war in Afghanistan if the movement's leaders call on him to do so.