SALT LAKE CITY — The sign “Atheists meet here” looked out of place with the tall administrative buildings of the Church of Jesus Christ of Latter-day Saints visible in the distance. A few dozen people milled around in the park nearby and chatted while some of their children sat cross-legged in the grass. A couple pointed and smiled at a quite different sign hanging from an apartment across the street: “We sustain the prophet.”

Dan Ellis, president of Atheists of Utah, reminded the crowd to remain cordial and friendly during the march. “When will we be eating babies?” someone from the crowd shouted facetiously, to laughs.

Despite the humor, the gathering represents a genuine clash of belief and nonbelief. The atheists were rallying during the national convention of the American Atheists organization, taking place over Easter weekend this year in Salt Lake City — which was also playing host to the Mormon general conference, one of the largest gatherings of the church. During the conference, local atheists assembled to march around the Temple Square walls. Former Mormons in the group signed official letters of resignation from the church, which they planned to hand deliver.

It was a strange scene in one of the most religious and conservative states in the country — and a level of activism that speaks to a new and more open outreach strategy by organized atheists. While the number of atheists in the country is hard to measure, there is no doubt it has risen. According to the Pew Research Center, the percentage of Americans who identify as atheist increased from 1.6 percent in 2007 to 2.4 percent in 2012. A third of adults under 30 are religiously unaffiliated.

The normalization of atheism has moved the topic of nonbelief from the dinner table to billboards and the street. Groups like American Atheists and countless online meet-ups and student groups across the country have begun reaching out more publicly, especially to members of a religious culture — like the Mormon Church.

The city was chosen for a couple of reasons, explained Dave Muscato, public-relations director for American Atheists. The nonprofit, whose members work for the separation of church and state through law and outreach, generally chooses heavily religious communities for hosting events. Utah was especially attractive this year because of the legal challenge to gay marriage from the state, which American Atheists saw as religiously motivated.

But according to Muscato, it was also to show support for the growing number of nonbelievers in Utah, 30 years after the organization last gathered there. “The religious landscape in that amount of time has changed so much,” he said.

His organization refers to those atheists who still attend church as “closeted.” Since the mid-2000s, with the publication of some popular pro-atheism books — Richard Dawkins’ “The God Delusion” and Christopher Hitchens’ “God Is Not Great” — the New Atheists have brought the subject, as well as supporters, more into the open, explained Muscato. He wants people to know that “there are atheists” even in Utah.