The word “Mormon” is out, says the president of the Utah-based church. But the proper term for what to call the faith and its followers is a mouthful.

In an announcement on Thursday, President Russell M. Nelson insisted that Mormons and non-Mormons alike stick to the term “the Church of Jesus Christ of Latter-day Saints.”

Mr. Nelson, 93, said that the policy change came to him in a revelation from God and that members of the church must work to adjust their vernacular. “The Lord has impressed upon my mind the importance of the name He has revealed for His Church,” he said in a statement.

The church’s updated style guide specifies that “Mormon Church,” “Mormons” and “Mormonism” are no longer acceptable. And no, you should not use the abbreviation “L.D.S.,” either.