When Green Bay's mayor wrote a letter to Pope Francis inviting him to make a pilgrimage to the "Shrine of Our Lady of Good Help"during his2015 trip to the U.S., the Freedom From Religion Foundation says he violated separation of Church and State.

Now the group says it's obtained documents that prove Mayor Jim Schmitt is using city staff and resources to promote a religious agenda.

To the Catholic Church, Pope Francis is a religious leader.

To Forbes magazine he's the 4th most powerful man in the world.

Which title motivated Mayor Jim Schmitt to write a letter inviting the Pontiff to Green Bay?

Freedom From Religion Foundation's Annie Laurie Gaylor says words like "pilgrimage" and signing the letter "your servant in Christ" make Schmitt'sintentions clear.

"He invited the Pope to come not as a dignitary, but as a religious figure," says Gaylor.

Which she says isagainst the law.

"Our concern is that he did this not as an individual Catholic but as Mayor of Green Bay using city letterhead and then our open records request has revealed on city time and also employing staff to further promote his personal religious mission. So his Chief of Staff and City Secretary were also using city time. For example to help set up meetings and create meeting agendas, so its just not appropriate,"says Gaylor. (You can read emails she obtained from the city below.)

Mayor Schmitt says he's done nothing wrong.

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Freedom From Religion Says City Emails Prove Wrongdoing