There is no single explanation for why people flock to the sanctuaries on Easter, but a lot of possibilities. They could be drawn to the grandeur of the day — clergy in vivid vestments, churches bedecked in lilies and aglow with candles, blazing lights and blaring trumpets, eloquent sermons and searing scriptures.
They might still consider themselves Christian but are too lazy or unmotivated for weekly or monthly attendance. They might feel guilty about forsaking their faith or drawn back by the power of memory.
Salt Lake City's magnificent Cathedral of the Madeleine will be packed with occasional worshippers, including some Mormons who want a taste of the majesty of Catholic liturgy on sacred days such as Easter.
"There will be a lot of complete strangers there, people the clergy have not ever seen before," says the Rev. Carl Schlichte, pastor at St. Catherine of Siena Newman Center on the edge of the University of Utah campus. "We'll see our numbers swell, too, but they tend to be relatives of parishioners or children of members who were more active in the past but aren't so now."
The phenomenon of these holiday attendees has been going on for decades.
"I don't know what draws them. Maybe they feel some connection to the day within themselves," says the Rev. Jeff Beebe, pastor at Our Saviour's Lutheran Church in Holladay, who expects to see his congregation double on Sunday. "Maybe it's just a spiritual feeling."
Whatever the reason, Easter is not a time for guilt-inducing sermons or shaming the un- or not-recently initiated, Beebe says. "We shape the service in a way that makes everyone feel welcome and can follow it. We try to keep it simple, rather than do things a little more insider-based."
That means no chanting, he says, which seems foreign to the occasional worshipper.
Beebe also will try to connect with a broad group of listeners, rather than offering a sophisticated theological treatise.
"Planting seeds is part of what we try to do on big days like Easter," the pastor says. "They might bear fruit down the road. Who knows where the Spirit leads?"
These days, though, the returnees are largely baby boomers — born between 1946 and 1964 — and Generation Xers — born between 1965 and 1980. Majorities in both groups experienced church as children.
However, many millennials, coming of age around 2000, have not had religious upbringings and thus wouldn't have even a "trace memories" of Easter.
One in four millennials "are unaffiliated with any particular faith," according to another Pew Research Center survey, and they are "significantly more unaffiliated" than boomers or Gen Xers.