The young man had never been to church before, and even this time he was there only to accompany his girlfriend.
After the service, held at the United Methodist church in Brewster, Mass., he approached the pastor and said, ''Wow, these benches look just like the ones in the courthouse!''
That's how ''unchurched'' the visitor was, as pastor Clinton Parker puts it, referring to how unfamiliar with mainstream Christian religious tradition the young man was.
His reaction, Mr. Parker says, symbolizes the challenge confronting mainline Christian churches throughout the United States. The size of their congregations is dwindling. Communities are changing - radically in some cases - and the mainstream ministry has lost touch with large segments of the population.
The responsibility lies at the doorstep of the churches themselves, say many people in the ministry. A gap - ethnic, generational, pop-cultural - has developed between old church ways and the lifestyle of new, different, and often younger groups.
This gap is pushing many churchgoers to seek out other sects, often ones that are more charismatic, fundamentalist, or national - such as Korean or Haitian. But over the decades, studies indicate that attendance at churches and synagogues has not radically changed. The latest figures from the Gallup Organization in Princeton, N.J., show that in 1939, 41 percent of respondents answered ''yes'' when asked whether or not they had attended a church or synagogue in the last seven days. For May 11-14, 1995, that percentage was exactly the same.
Yet today's churchgoers may listen to different music, admire different people, spend their leisure time in different ways.
''Churches need to do better at connecting with people,'' says Connie Bickford, an ordained minister and director of professional education at Boston University's School of Theology. ''A lot of people are not being reached by the churches in existence, but we believe they are engaged in a search for a spiritual connection they don't even know how to name. They are searching.''
Many pastors of so-called mainline Christian churches are well aware of this and for years have been trying to make that connection. Initiatives to create churches for new groups of people, to improve existing churches, and contact unaffiliated people are now commonplace.
But now, a highly organized program to meet this need is being held in conjunction with Boston University's divinity school. The New Church Development and Congregational Transformation Program at BU's School of Theology, and the United Methodist Church (UMC), have convened a group of United Methodist ministers for a two-week session of skill-honing and eye-opening.
Like executives taking brush-up courses at business schools on trends affecting the economy, these pastors are plunging into classroom sessions, field excursions, and workshops to find out about trends in religion.
In the process they are learning how to reach out. They are studying everything from how to canvas a community to determine its nature and needs, to what kind of electronic speakers work best with pop music.
Sessions range from the nitty-gritty to the inspirational. One of them is conducted by Juan Vergara, a minster from Cuba who is pastor of the Primera Iglesia Bautista (First Baptist Church) in Everett, Mass. In impassioned phrases he urges his listeners to enter school classrooms, drive around the community, and talk to other churches. He is like a sales manager motivating his staff.
In another class, the instructor could as well be explaining how to start a new McDonald's franchise. He draws graphs on the blackboard, details ways of phoning and networking, and lays out tactics for determining the nature and needs of a church's neighborhood.
''The majority of our churches, other than nondenominational new churches, are aging,'' says Craig Miller, director of New Congregational Development for UMC. ''We just had a study out showing that 60 percent of our membership is over the age of 60. It also applies to many other denominations. They have have been the mainstay of many churches across the country. They give the most. They are the most faithful in worship.''
James Craig, who serves on the UMC's Global Ministries board, adds, ''We are working with churches that once had a peak membership, in some cases, of 1,500 or 2,000. But we have dwindled down because of changing dynamics of a community.''
Parker suggests one reason for this: ''When we rejected a lot of the institutions in the Vietnam protesting era, some of these people didn't find the church responsive.''
To Mr. Craig, that raises the question ''How does the older generation pass the faith on to baby boomers, those born between 1946 and 1964, and to the gap generation - Generation X, age 14 to 30?''
''The church focuses a lot on getting the baby boomers and the younger children,'' he says, ''but we're not good at getting youth and young adults.''
But the potential is there to revive and replenish the congregations, and that's what the people at the BU conference are gearing up to do. Talk to any of them and the target seems to be not ''numbers'' but a vital link to the lifestyle and aspirations of individual people.
As Mr. Miller puts it, ''How do we speak to people in their own heart language? If you start a congregation in Spanish, for instance, you must look at the people's culture. Most GI generation churches use organ music. Well, not too many people listen to organ music on the radio today. We might have to use guitars, drums, or synthesizers in our worship.''
Parker agrees. ''The hot button issue is the style of worship, the style of music, and other aspects,'' he says. ''Today you can build a sermon on the film 'Forrest Gump.' The spoken word of the preacher is not necessarily the center.
''One approach, called 'Common Worship,' uses hymns. Another, the 'Book of Common Song,' uses contemporary Christian music, video clips, dramas, as the way to present the gospels. There's a huge controversy between those different models.''
Other factors also figure in the decline of membership and the need for reaching out in new ways. ''People today have longer, more stressful work weeks,'' says Don Bommarito, associate council director of the Council on Ministries for the UMC's California-Pacific Annual Conference.
''Sunday becomes a time for them to relax. For the older generation it was a prideful thing to belong. Today people are saying: 'Does it meet my needs? What am I getting out of it?' Many churches haven't adapted in a way that says: 'We value who you are.' ''
But underlying it all, for Mr. Bommarito and most other ministers is a basic mission: ''The challenge of the church is the same one that's been there since day one,'' Parker says.
''It is how best to speak to the hearts of people when they ask 'Who am I?' We want to be there in whatever vehicle is necessary to communicate to them that God loves them and cares for them. We're trying now to define what that vehicle is.''