(RNS) It used to be that Americans focused their religious lives around brick-and-mortar structures — churches, synagogues, mosques and temples — for worship, study and assembly.

Members of various faith communities considered those buildings the center of their spiritual lives as they gathered for religious rites of passage including baptisms, baby namings, bar/bat mitzvah ceremonies, confirmations, weddings, and funerals.

Inside those sacred spaces with their steeples or domes or stained-glass windows, Americans followed the men — it was nearly always men — who donned colorful vestments as a visual validation of their religious authority.

Not any more.

There are enormous changes afoot, and failure to respond will mean clergy and their once dominant institutions will be pushed to the sidelines of American life. The fancy sociological term for such irrelevancy is “marginalization.”

The religious model that dominated American life is weakening, and even disappearing, in the face of irreversible spiritual and technological changes. America’s religious institutions can get ahead of this wave, or be swallowed under by it.

Not too long ago, it was difficult for laypeople to acquire and then study a sacred text on their own beyond the omnipresent family Bible. The writings of ancient church fathers, medieval theologians, or even contemporary religious leaders were generally confined to dusty shelves inside large public libraries or seminaries.

Within Judaism, for example, those who wanted to venture into the literature of post-biblical Judaism — especially the 5,894 pages of the Talmud — were stymied unless a nearby synagogue or rabbinical school offered such study.

The Internet has changed all that. Want to know how the Christian theologian Thomas Aquinas was influenced by the Jewish philosopher Moses Maimonides? It’s just a Google search away. Want to read different English translations of the same scripture verses? There’s an app for that.

Men and women no longer have to meet together in a designated building to share spiritual beliefs or study. Skype, Facebook, Twitter and YouTube have shattered geographical borders and psychological barriers. Now you can pray in real time with someone half a world away.

Don’t like your local synagogue? You can log in to one on the other side of the country. Don’t trust what your pastor said in church on Sunday? Log on to your favorite blog or website to find out for yourself.

In short, the neighborhood synagogue or church is being supplanted by the rapid globalization of all things religious.

Religious commitment has always been held in tension between public “externals” (clergy, buildings, institutions) and private “internals” (personal prayer, meditation or study). Increasingly, the line between the two is so blurred as to be invisible.

Recent surveys indicate that Americans, perhaps the world’s greatest consumers, are shopping around to find the “best and latest” elements to suit their religious needs. Call it “spiritual consumerism.”

It can mean many things to many people: joining a Protestant megachurch with custom-tailored niche ministries, or opting for a small living-room fellowship that offers intimate study and prayer, or a do-it-yourself private spirituality that has little to no connection to any group, large or small.

That’s not all. There’s the impact of feminism on religions that have been male-dominated; liberation theology that challenges a society’s religious and political order; and interfaith encounters — increasingly, within people’s own families — that do not require the approval or guidance of religious authorities.

Lay people are staking out moral and ethical positions on issues that were once the exclusive domain of an educated hierarchy. Clergy can either fight and trivialize this irreversible movement and be marginalized, or embrace it and find ways to meet the needs of wandering flocks while still preserving their eternal messages.

(Rabbi Rudin, the American Jewish Committee’s senior interreligious adviser, is the author of the recently published “Christians & Jews, Faith to Faith: Tragic History, Promising Present, Fragile Future.”)