For the last three years, high-school senior Chase Windebank has been meeting with other students during a designated free period to discuss their Christian faith, pray and even sing together.

But on Sept. 29, the assistant principal of Pine Creek High School in Colorado Springs, Colorado, told the students it has to stop because it violates the "separation of church and state."

Religious discussion gatherings, the school insists, can only take place before or after school hours.

Now, with the help of attorneys from Alliance Defending Freedom, or ADF, Windebank is suing the school to lift the ban and restore what he says are protected First Amendment rights.

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"Far from being unconstitutional, religious speech is expressly protected by the First Amendment," says ADF Legal Counsel Matt Sharp, "and public schools have no business stopping students from praying together during their free time."

"Public schools should encourage the free exchange of ideas," adds ADF Senior Legal Counsel Jeremy Tedesco. "Instead, this school implemented an ill-conceived ban that singles out religious speech for censorship during free time."

The controversy swirls around use of the "Seminar" period, a 40-minute window when students with adequate grades are permitted a degree of free time during the school day.

According to court documents, students excused from Seminar to enjoy the free time are permitted to engage in "a virtually unlimited variety of activities," including free movement in the school's public areas, discussions with other students, texting, getting a snack, visiting with teachers or even scheduling official meetings of school clubs.

The one thing Windebank and his fellow Christians have been told they can't do, however, is talk about God.

According to letter issued by school-district attorney Patricia Richardson, Windebank's prayer gathering is a "non-curriculum related group" that can only meet during "non-instructional time," defined as before or after the school day. No non-instructional groups, Richardson insists, are allowed to meet during Seminar.

The ADF, however, disagrees, asserting the school affords to students excused from Seminar "the same type of freedom that is often found during recess or lunch, when students have long been recognized to have the right to engage in non-disruptive expressive activities."

And according to the lawsuit, Windebank and his fellow Christians have never been accused of being "disruptive" in any way.

"During the open time given to students during Seminar, students are free to meet in informal groups to discuss any topic: their plans for the weekend, a new movie or television show, or even the usual school gossip that circulates among teenagers," the lawsuit charges. "The District does not limit the students' speech and expression during this open time, unless they engage in religious expression" [emphasis added].

The lawsuit seeks the ban be lifted, a declaration of the ban as unconstitutional, attorneys' fees and "nominal damages in the amount of one dollar for the violation of [Windebank's] constitutional rights."