The man arrested for setting fire to the mosque of Omar Mateen, who murdered 49 people at a gay nightclub in Orlando, describes himself as a Jew for Jesus, a religious sect that believes Jesus is the messiah.

Joseph Michael Schreiber was booked into the St. Lucie County Jail on Wednesday on charges that he set fire to the Islamic Center of Fort Pierce, Florida, just after midnight on Sept. 12. Photos from inside the small mosque, which has received threats since Mateen’s ISIS-inspired terrorist attack, show collapsed walls and fire damage. Schreiber faces at least 30 years in prison if convicted because of his prior felony history, according to court documents. Police said Schreiber confessed after he was arrested.

Schreiber’s Facebook profile features abundant anti-Muslim rhetoric. In one post, he proclaimed “ALL ISLAM IS RADICAL.” And after Micah Johnson killed five police officers in Dallas, Schreiber shared a post attempting to link the shooter with the Muslim Brotherhood.

The first clues to Schreiber’s religious beliefs also come from his Facebook page, where his cover photo features the seal of messianic Judaism. It shows a menorah and a Jesus fish intersecting to form the Star of David.

Many of Schreiber’s three dozen Facebook friends also self-identify with Messianic Judaism, either proclaiming themselves members of the faith in their profiles, or saying that they work at Messianic Jewish synagogues.

Previous media reports described Schreiber, who spewed anti-Muslim hate on Facebook, as Jewish. But Messianic Jews, colloquially known as Jews for Jesus, occupy a nebulous space in the religious landscape. (Jews for Jesus is also a recognized nonprofit organization that promotes a type of Messianic Judaism.)

Many adherents would describe themselves as Jewish, and some even fit the bill under Jewish law, having been born to Jewish parents or converted into traditional Jewish denominations. They often refer to their religious leaders as rabbis, observe Jewish holidays, and conduct services in Hebrew. Yet Messianic Jews accept Jesus as the messiah, in stark contrast to mainstream Jews who do not. They are typically not acknowledged as Jewish by mainline Jewish denominations, and often grouped as a type of evangelical Christianity.

They are “outside the parameters of accepted Jewish thinking,” Bruce Benson, the rabbi of a Reform Jewish temple briefly attended by Schreider, told The Daily Beast.

“Because once you accept Jesus as your messiah—which, I’m 100 percent fine with that—but once you do that, you’ve accepted a messianic imaging that really sort of separates you out from the Jewish community,” Benson said.

And, while Jews don’t typically proselytize to people outside the religion, Messianic Jews are known for their recruitment efforts. Jews for Jesus (the registered 501c3, in this case) is particularly known for dispatching flocks of recruiters to accost people in public areas.

But Schreiber also openly admitted to being a Jew for Jesus to Rabbi Benson when he showed up to a Saturday Torah study earlier this year. Fort Pierce’s Temple Beth El Israel is a Reform congregation and don’t believe that Jesus was a messiah or a son of God, but Benson says he welcomed Schreiber to the Torah study as he would any other non-Jew.

“He wanted to study,” Benson said. “Clearly our visions are a tad different, but that’s OK. It would be the same as if he walked in and said he was Catholic or Methodist or Baptist.”

“And, bluntly, I appreciated that he was clear in his belief. I had no interest in getting him to change his beliefs, because frankly, it wasn’t gonna work,” he added.

Schreiber only stuck around for three or four lessons, according to Benson. The rabbi doesn’t remember him being angry or confrontational, or trying to push his beliefs on members of the congregation.

“If I’m selling Chevrolets and you’re pushing Buicks, get out of my house,” Benson said. “But he wasn’t.”

In fact, Benson might’ve all but forgotten about Schreiber had his father, Arthur, not shown up on the synagogue’s steps on Wednesday evening.

It turns out Schreiber’s grandfather, also named Arthur, was once a member of Temple Beth El Israel. He left many years ago and had since passed away. The younger Arthur Schreiber and his wife were not members of the synagogue, and had no contact with the temple.

But when police showed up at the Scheibers’ door on Wednesday, Joseph’s father got in his car to drive around.

“And apparently, in answering his own issue of what do I do, where do I go, came to the temple,” Benson said.