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SYDNEY, Australia — Sister Joan Chittister, a well-known American nun, feminist and scholar, was looking forward to speaking at a Catholic education conference in Australia next year, figuring there would be plenty to discuss in a country where Catholic schools educate roughly one in five children.

But then Sister Joan, 83, received an email a few weeks ago effectively telling her not to come, saying that the Archbishop of Melbourne, Peter Comensoli, had not endorsed the invitation.

No reason was given, she said. But to Sister Joan and her supporters, the message was clear: The leaders of the church don’t like her ideas — especially her call to empower women and laypeople — so they plan to suppress them.

“It is pathetic,” Sister Joan said on Monday in an interview from Erie, Pa., where she has lived and worked with the needy for most of her life. “These teachers for the next generation of thinkers are being denied the right to pursue ideas.”