Recently the citizens of Boise have been engaged in a community discussion about whether a monument containing the Ten Commandments should have been removed from a local public park. Sometime in the 1950's or 60's the Eagles erected the monument in the park, which is clearly public property.

In 2003, a controversial religious figure from outside Idaho asked the Boise City Council to erect a monument expressing his religious belief that gay people, such as Matthew Shepard who was murdered in Wyoming because he was gay, will "burn in hell."

In response, the City of Boise had the monument removed from the park. It was relocated to the grounds of a local Episcopalian church in a prominent location in downtown Boise.
What part of the constitution is implicated in this case? Was the City of Boise's action constitutional? Was it correct? What two "rights" might be at issue here?