A virulent anti-Christian organization is threatening a Mississippi school district after a pastor delivered a prayer and sermon at a convocation for teachers this month.

The American Humanist Association sent a letter to the superintendent of the Jackson Public School District on Monday claiming they were representing an anonymous teacher who attended the event.  The AHA claims the teacher said attendance at the event was mandatory.

The speaker was Pastor Roy Maine, who works as an electrician in the district.  He was invited to deliver an opening prayer and he offered words of exhortation during his invocation.

The anti-Christian group says their anonymous client described the event as “one long church service.”

Attorney Monica Miller of the anti-Christian group said that if the school does not bar the use of religious speech at events they could file a lawsuit.

“This letter serves as an official notice of the unconstitutional activity and demands that the school district terminate this and any similar illegal activity immediately. To avoid legal action, we kindly ask that you notify us in writing within two weeks of receipt of this letter setting forth the steps you will take to rectify this constitutional infringement,” Miller wrote.

The school district acknowledged receiving the letter but did not offer a public response to the letter’s content.