For years, Mark Zuckerberg identified as an atheist—at least on his profile page. But in a holiday message posted on Dec. 25, the Facebook CEO nods at a potential return to religion.

Zuck wished his friends a “Merry Christmas and Happy Hanukkah from Priscilla, Max, Beast and me!,” to which one user replied “Aren’t you an atheist?”

“No,” Zuckerberg responded. “I was raised Jewish and then I went through a period where I questioned things, but now I believe religion is very important.”

The Facebook founder has alluded to his spirituality in the past. During a trip to China in 2015, Zuckerberg ”offered a prayer for peace and health for the world and for my family” in front of Wild Goose Pagoda in Xi’an. “Buddhism is an amazing religion and philosophy, and I have been learning more about it over time,” he wrote on Facebook at the time. “I hope to continue understanding the faith more deeply.”

Atheism is on the rise in America: According to the Pew Research Center, the number of people who identify as atheist, agnostic, or religiously unaffiliated rose to 22.8% in 2014, from 16.1% seven years earlier. Last month, the 1998 Frank R. Wolf International Religious Freedom Act, which safeguards religion minorities abroad, was amended to include Americans identifying as atheist. And in 2013, Pope Francis gave an impassioned homily highlighting God’s unconditional love, “even [for] the atheists.”

In that same homily, Pope Francis referenced the Golden Rule: treating others as you’d like to be treated. The impact people have on one another has always fascinated Zuckerberg, and was part of what drove Facebook’s creation way back in 2004.

“May the light of your friendships continue to brighten your life,” Zuckerberg wrote at the end of his holiday message, “and our entire world.”