More than 560 of Schulz’s nearly 17,800 Peanuts newspaper strips contain a religious, spiritual, or theological reference. To put this into perspective, Schulz only produced 61 strips featuring the famous scene where Lucy pulls the football away from Charlie Brown as he tries to kick it. Particularly later in his career, the religious references came so frequently that pastors and religious publications regularly requested permission to reprint Peanuts strips, which Schulz almost always granted.

Schulz’s most recognizable reference to religion occurs in the Charlie Brown holiday special exploring the “true meaning of Christmas.” Realizing that the holiday’s secular accouterments did not form the essence of Christmas, Linus reads the story of Jesus’s birth directly from King James Version’s account in the Gospel of Luke. At the time, less than 9 percent of Christmas episodes and specials contained religious references.

On rare occasions, Schulz stepped out onto more spiritually shaky ground. In 1963, when debates over the role of religion in public school were raging, Schulz penned a somewhat controversial strip in which Sally recites the pledge of allegiance from her classroom desk and concludes with a resounding, “Amen!”

“I preach in these cartoons, and I reserve the same rights to say what I want to say as the minister in the pulpit,” Schulz once said.

But the Peanuts preacher was not of the “hellfire and damnation” variety you might expect to find in a fundamentalist church. He did not attempt to shame skeptics, level judgments, and stated he “didn’t have any axes to grind.” Schulz was also no evangelist and made no effort to convert non-believers. (He actually once offered a critique of evangelists with a strip in which Linus hands out religious tracts to neighborhood families.) Instead the cartoonist just let who he was and what he believed leak into his strips.

“You can grind out daily gags, but I’m not interested in simply doing gags,” Schulz would say. “I’m interested in doing a strip that says something and makes some comment on the important things in life.”

Schulz converted to Christianity shortly after returning from a deployment in World War II, and the experience sparked a love inside of him for sacred literature. He became a voracious reader of theological commentaries, and the margins of his personal Bible were filled with hand-written notes. He was a long-time Sunday School teacher at churches in the Midwest and California, even leading one group through a study of the entire Old Testament.

This may be why many of the religious references in the Peanuts were drawn directly from sacred texts. In June of 1952, the somewhat sad and self-deprecating Charlie Brown borrowed Solomon’s words from Ecclesiastes 1:14: “All is vanity!” In December of 1955, a shivering Snoopy found solace in Jesus’s words from John 16:33: “Be of good cheer, Snoopy … Yes, be of good cheer.”