In 1973, Vanderbilt medical school student Jim Fletcher was having a spiritual crisis. He found himself surrounded by students and professors who used science to dismiss Christianity, claiming it is impossible to know spiritual truth with certainty.

He decided to take a leave of absence from medical school, and with his wife sought out a place he had heard about in the Swiss Alps called L'Abri. Founded by philosopher, apologist, and pastor Francis Schaeffer in 1955, L'Abri (French for "the shelter") had become a haven for disillusioned Christians, curious backpackers, and seeking non-Christians.

"I spent time with living, breathing Christians who helped me understand there really was an intellectual integrity to what I believed," Fletcher said. "I studied science and religion and came to see that science stood on the shoulders of Reformation thinking."

Fletcher left L'Abri determined to finish medical school. "All of a sudden it made sense to pursue intellectual things, so I could use my intellect for the glory of God," he told Christianity Today. Fletcher is now a physician in Georgia.

In March, more than 1,000 of those who either have worked at or attended L'Abri, or who simply have been influenced by Schaeffer himself, gathered in St. Louis to celebrate the ministry's 50th anniversary.

L'Abri started with the Schaeffers welcoming their daughters' university friends into their small Swiss chalet on weekends. Today it has grown into a network of seven residential branches where "students" (anyone, age aside, who attends one of the fellowships) can visit for a few days or a few months. About 75 percent of those who attend are university age, but the branches regularly welcome older students as well.

The way Schaeffer led such ...