(RNS) The sign on the campus of the University of Tex-San Antonio was bound to get attention: “Trade in holy text 4 porn.”

The annual event sponsored by the Atheist Agenda student group, “Smut for Smut,” sparked enough protest and controversy that police were called in to monitor the scene on Monday (March 1).

“Smut for Smut” began in 2005 when students were offered free pornographic magazines in exchange for Bibles, Torahs, Korans and other sacred texts, according to The San Antonio Express-News.

This year, Christians rallied against Atheist Agenda members, which prompted a group of agnostics to plead for peace, according to reports. The university, however, does not condemn the event or the protestors.

“As long as students are not violating laws or violating the Constitution, they have the freedom of speech and assembly,” said UTSA spokesman David Gabler.

Ten religious texts were collected.