In its recruiting efforts, the U.S. Marine Corps deliberately invokes some of the most demanding standards in the world. It touts the resulting solidarity and exclusivity of those who manage to measure up. You've probably heard their slogan: “The few. The proud. The Marines.” Other services sometimes have to struggle to achieve their recruitment goals. The Marines consistently meet or exceed theirs. And almost uniformly, current and former Marines are fiercely proud of their service. "Once a Marine, always a Marine.”
It's sometimes said that the same is true for religions.