July 8. On this date in 1970, the Universal House of Justice wrote that "a Baha'i who continues to believe in Baha'u'llah cannot withdraw from the Baha'i Community. While he believes in this Revelation he is subject to its laws."

July 8. On this date in 1970, the Universal House of Justice wrote that "a Baha'i who continues to believe in Baha'u'llah cannot withdraw from the Baha'i Community. While he believes in this Revelation he is subject to its laws."

Any member of the Baha'i Community who finds that he does not believe in Baha'u'llah and His Revelation is free to withdraw from the Faith and such a withdrawal should be accepted. But a Baha'i who continues to believe in Baha'u'llah cannot withdraw from the Baha'i Community. While he believes in this Revelation he is subject to its laws. Therefore your National Spiritual Assembly was not correct in accepting Mr. ...'s withdrawal from the Faith. In his very letter of withdrawal Mr. ... reaffirmed his belief in the Faith. You should, therefore, immediately reinstate him and so inform him. Of course, he may well wish to remain inactive, and if so his wish should be respected, but he should know that he is a member of the Baha'i community.
Letter from the Universal House of Justice, dated July 8, 1970

This letter is referenced on page 128 of Developing Distinctive Bahá'í Communities: Guidelines for Spiritual Assemblies, which the National Spiritual Assembly of the United States published in 1998 "to assist Local Spiritual Assemblies in their efforts to rise to the new stage in the exercise of their responsibilities."
It is also referenced in various letters, such as this one from October 18, 1990, written by the National Spiritual Assembly of the United States to an individual who had written them to resign from the Bahá’í Fatih.