Travelers have always followed guidebook advice religiously, scurrying from one historic site to the next, but for some Americans the book they’re taking their cues from has changed. Move over, Frommer’s. It’s the man upstairs’ turn.

Menlo Consulting Group found in a recent survey that one-third of Americans who travel abroad said they hoped to take a faith-based trip in the future and 9.5% of travelers polled had already completed a religious journey. This percentage encompasses 4.5 million travelers and means big business for travel companies, particularly those offering guided tours of holy sites around the world.

Faith-based travel spans virtually all religions. In doing my research for this post, I found pilgrimage packages for followers of Jainism and Zoroastrianism, plus discovered that Scientologists often visit Clearwater, Florida to see the worldwide spiritual headquarters of the Church of Scientology and the Super Power Building.

Though it’s certainly a trend on the rise, religious travel is hardly a new concept. Ever since Mohammed wrote down the fifth pillar of Islam, which commands all Muslims to make the hajj, or pilgrimage to Mecca, men and women have been inspired by their belief systems to seek out new corners of the world. But it’s important to remember that religious travel is a broad category that includes several kinds of trips: pilgrimages and visits to holy sites or religious leaders, service-oriented trips to aid a community, and, most recently, first-class travel to more off-the-beaten-path religious sites.

At one time, a Christian might have dreamed of visiting Golgotha. Today, that same individual can sign up for “Christian England and The World of C.S. Lewis” or the “Lourdes and the Shrines of France” tour. Sure, Jewish Americans still enjoying visiting an Israeli kibbutz, but today’s travelers can also take a Jewish singles cruise. And Mormons who might at one time have driven to Salt Lake City to see the temple, now may stroll through the Sacred Grove in upstate New York or even cruise Alaska with fellow followers.

Have you ever considered taking a faith-based trip? If you have taken one, where did you go and why?