About 50 Boulder High School students walked out of class Thursday to protest the daily reading of the Pledge of Allegiance and recited their own version, omitting "one nation, under God."
The students say the phrase violates the constitutional separation of church and state.
They also say the daily reading of the pledge over the school public address system at the start of the second class takes away from education time and is ignored or mocked by some students.
A state law passed in 2004 requires schools to offer the opportunity to recite the pledge each day but does not require students to participate.
The protesting students, members of the Student Worker Club, want administrators to hold the pledge reading in the auditorium during each of the school's two lunch periods for any students who want to participate.
Otherwise, they said, they plan to walk out each Thursday when the pledge is read and recite their version, which omits the reference to God and adds allegiance to constitutional rights, diversity and freedom, among other things.
"Boulder High has a highly diverse population, not all of whom believe in God, or one God," said Emma Martens, a senior and president of the club, which has about a dozen members.
"We didn't think it was fair for the whole school to have to listen to it. It's almost religious oppression," she said.
Principal Bud Jenkins told the Camera newspaper on its Web site Thursday the pledge will not be moved, but added he was proud of the students for standing up for their beliefs.
It was not immediately clear what discipline, if any, the protesting students would face.