Pope John Paul II, visibly tired after a 14-hour flight and using a cane on the tarmac, arrived in Manila as a surging sea of a million Filipinos welcomed him to the only predominantly Roman Catholic country on his grueling, four-nation tour of Southeast Asia. The visit entailed some personal risk, as Filipino authorities had warned of a possible terrorist attack on airlines during the pontiff's visit. (Last week, they arrested a man after finding bomb-making materials in a nearby apartment.) Today, police arrested a man found carrying a pistol along the papal route, deployed bomb-sniffing dogs around the Papal Nunciature and even examined boxes of chocolates carried by nuns. The pontiff, undeterred, told the throng the church in the Philippines has "a special vocation" to spread Christianity among the ancient cultures of Asia.