"We have just enough religion to make us hate," wrote Jonathan Swift, "but not enough to make us love one another." A lifelong religious controversialist, the 18th-century Irish satirist definitely knew whereof he wrote. After all, it's fewer than 20 years since Protestants and Catholics in Northern Ireland quit dynamiting each other's gathering places.Even here in the United States, it often seems that picking fights over religion increases during the Christmas season.