A Christian legal group has sued a school district on behalf of a 10-year-old boy who claims his rights to religion and free speech were violated when he was not allowed to wear a Jesus costume during Halloween activities.

The complaint, filed in federal court Tuesday by the Alliance Defense Fund, says officials at Willow Hill Elementary School in suburban Glenside told the boy Oct. 31 that he could not wear his faux crown of thorns or tell others he was dressed as Jesus.

The principal, Patricia Whitmire, told the boy's mother that the costume violated a policy prohibiting the promotion of religion, according to the lawsuit. Whitmire suggested that the fourth-grader, whose costume included a robe, identify himself as a Roman emperor, the suit states.

Though the boy's costume was rejected because of its religious nature, the principal allowed other students to dress up as witches and devils, according to the lawsuit, which identified the boy only by his initials.

Whitmire and the Abington School District are named as defendants. District attorney Ken Roos said Wednesday that he had not seen the suit and that school officials "feel like we've been a little bit ambushed here."

The boy and his mother are Christians who object to the pagan elements of Halloween, but the mother did not want the boy isolated for refusing to wear a costume, according to the lawsuit.

Willow Hill officials required students to wear a costume to participate in a parade and party; those who did not were sent to the computer room, the suit says.

The boy no longer attends the school.

The Alliance Defense Fund is based in Scottsdale, Ariz.