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

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

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