The question was so simple that Haddon Robinson wasn't sure he had heard it correctly.

"What is Christmas?", asked the man in the next airplane seat, once he learned that he was chatting with a seminary professor. The businessman thought he knew, since he was an ordinary American who had grown up surrounded by old movies and television specials. Then he asked, "What is Easter?" That led to, "What do you mean by 'resurrection?' " Robinson described the biblical accounts of God raising Jesus from the dead.

"This man said to me, 'Do all Christians believe that?' I said, 'All Christians should believe that,' " said Robinson. "Then he said, 'That's interesting. I think I knew about Christmas. But I didn't really know about Easter.' "

This puzzled Robinson, but later something clicked. Some Christmas hymns have made it into popular culture and almost everyone hears snippets of the story year after year. But where -- via mall, multiplex and mini-satellite dish -- would anyone soak up Easter images? For millions of viewers the resurrection is what happens at the end of "The Matrix."

If missionaries came to America, they would immediately spot the dominant role played by mass media and, especially, visual entertainment media. They would study the moral and religious messages in mass media, seeking insights into the lives of potential converts. This is how missionaries think. But this is not how religious educators think and, thus, few clergy are taught to think like missionaries.

Robinson has been studying these issues since the mid-1950s, during his doctoral work in communications at the University of Illinois. Today, he is a distinguished professor at Gordon-Conwell Theological outside Boston and, in 1996, received national media attention when Baylor University named him one of the top 12 preachers in the English-speaking world.

Effective speakers study the forces that shape the people to whom they speak, said Robinson. Today, that means taking visual media seriously.

"Television is omnipresent," he said, in a sermon that swept from oral traditions and clay-tablet libraries to satellites and computer networks. "The way in which people get ideas, the way in which they shape their ideals, comes not because they read books, but because they see it, they visualize it. It's on television. ...

"That has shaped the way we think. ... It affects the way that we preach. It affects the heart and core of communication."

Robinson preached that sermon exactly 10 years ago, while serving as president of Denver Seminary. Little has changed. Robinson said that he knows of no seminary that requires future ministers to take a single course on how mass media affect American life.

If anything, the situation has gotten worse, he said. While the ecclesiastical elites ignore the subject, megachurches often uncritically embrace virtually every new technology. Many churches are adding expensive digital equipment in their sanctuaries and leaping into multimedia music, drama, humor and sermons illustrated with movie and TV clips. Clergy quickly discover that they're expected to use this gear in every service. The audience demands it.

"The pastor is thinking, 'Now that I have all of this stuff, where can I throw it in?'," said Robinson. "All of a sudden, rather than thinking of the most effective way to communicate a message, you're thinking about all that money you've spent. ...You're thinking about media, where before you were thinking about your message."

Robinson's advice to preachers, young and old, is that they worry less about using mass media and more about learning what is shaping the souls of their listeners. Today, every flock includes many listeners who understand little or nothing about the Bible or basic doctrines. In fact, he said, their heads and hearts are full of conflicting images and values, the result of years of spiritual channel surfing.

This was already true a decade ago. Robinson said that preachers must realize that they work in a hostile technological environment, one that "communicates with images. It doesn't come out and argue. It just simply shows you pictures, day after day after day after day. Before you realize it, in the basement of your mind, you discover that you have shifted your values and many times you've lost your faith."