A federal judge on Wednesday barred the Indiana House from opening its sessions with specifically Christian prayers, ruling that such prayers amount to "an official endorsement of the Christian religion."

Judge David Hamilton advised House Speaker Brian Bosma that invocations given in the Legislature should not use the name of Jesus Christ or Christian terms such as savior.

Of 53 opening prayers given in the House during the 2005 session, 41 were given by clergy identified with Christian churches and at least 29 mentioned Jesus Christ, according to court documents.

Hamilton said that practice "amounts in practical terms to an official endorsement of the Christian religion."

"All are free to pray as they wish in their own houses of worship or in other settings," Hamilton wrote. "Those who wish to participate in a practice of official prayer must be willing to stay within constitutional bounds."

Bosma called the ruling an "intolerable decision" that threatened free speech. He said he has directed his lawyers to study ways to overturn the decision.

The Indiana Civil Liberties Union challenged the prayer practices in a lawsuit on behalf of four people, including a Quaker lobbyist, who said they found the tradition of offering the usually Christian prayers offensive.

"The prayers send a very powerful message of exclusion to those who are not of that denomination," said Ken Falk, the ICLU's legal director.

Dozens of religious leaders signed a statement saying House prayers should honor religious diversity.