"I AM THE LEAST PROBABLE GUY TO BE THE CEO OF THIS," SAYS Bill McCartney, 57. After all, the controversial former college football coach who runs Promise Keepers, the 2.7 million-strong Christian men's movement, was once an alcohol-fueled workaholic. Tapping into deep concerns about men's eroding role in the home, his group burst into national attention in October, when an estimated 500,000 adherents (no women, please) gathered on Washington's National Mall to hold hands, pray and beg forgiveness for their shortcomings. The gathering was one of the largest religious convocations ever in the capital. It was also a personal victory for the mercurial McCartney, out of whose own turbulent history the seven-year-old Promise Keepers grew. During 13 years as head coach at the University of Colorado, McCartney, who became a born-again Christian in 1974, drew fire for mandating team prayer and speaking out against abortion. At the same time, he writes in his recent book Sold Out: Becoming Man Enough to Make a Difference, his family was approaching "the brink of ruin." Lyn-di, his wife of 35 years, became bulimic and suicidal. His daughter Kristyn, 28 (one of his four children), had two babies out of wedlock. And McCartney does not deny reports that he had an affair in 1973. But eventually his faith led him to mend his ways. He quit his $350,000-a-year job in 1994 to spend more time with Lyndi and now spreads the message that husbands must become the leaders of their families. That goal alarms some critics. Says National Organization for Women president Patricia Ireland: "He envisions a world where women take a backseat." Perhaps, but talk-radio host Don Imus reaches a more optimistic conclusion. "Anytime you can get several hundred thousand men together without liquor and no football game," he says, "it's an achievement."