Since I work at a school where seemingly no one hides their faith, but I am forced to hide my atheism, the question seems silly. I wish that more of my colleagues would hide their faith. At graduation last year, students led two prayers. The act meant something to everyone in the audience. To me, it meant that I was part of an oppressed, invisible minority. To them, it was probably profoundly meaningful in some way.
Jesus said in Matthew 6 that you're not supposed to be out there praying on street corners; prayer should be private. If you're a Christian, how could you possibly think it was right to pray at secular festivals such as graduations and football games? Why would you consider it necessary to proclaim your faith to nonbelievers.