January 15. On this date in 1950, the National Spiritual Assembly of the United States instituted the first celebration of World Religion Day ("a celebration of the need for and the coming of a world religion for mankind, the Bahá'í Faith itself") to promote the Bahá'í Faith in an ostensibly interfaith setting.

January 15.  On this date in 1950, the National Spiritual Assembly of the United States instituted the first celebration of World Religion Day ("a celebration of the need for and the coming of a world religion for mankind, the Bahá'í Faith itself") to promote the Bahá'í Faith in an ostensibly interfaith setting. World Religion Day is celebrated on the third Sunday in January.

On October 22, 1968, a letter of the Universal House of Justice to the Local Spiritual Assembly of Chicago stated, "Your letter of September 30, with the suggestion that 'there should be one day in the year in which all of the religions should agree' is a happy thought, and one which persons of good will throughout the world might well hail. However, this is not the underlying concept of World Religion Day, which is a celebration of the need for and the coming of a world religion for mankind, the Bahá'í Faith itself. Although there have been many ways of expressing the meaning of this celebration in Bahá'í communities in the United States, the Day was not meant primarily to provide a platform for all religions and their emergent ecumenical ideas."

1710. World Religion Day, Purpose of
Your letter of September 30, with the suggestion that 'there should be one day in the year in which all of the religions should agree' is a happy thought, and one which persons of good will throughout the world might well hail. However, this is not the underlying concept of World Religion Day, which is a celebration of the need for and the coming of a world religion for mankind, the Bahá'í Faith itself. Although there have been many ways of expressing the meaning of this celebration in Bahá'í communities in the United States, the Day was not meant primarily to provide a platform for all religions and their emergent ecumenical ideas. In practice, there is no harm in the Bahá'í communities' inviting the persons of other religions to share their platforms on this Day, providing the universality of the Bahá'í Faith as the fulfillment of the hopes of mankind for a universal religion are clearly brought forth."
(From a letter of the Universal House of Justice to the Local Spiritual Assembly of Chicago, October 22, 1968)

On January 9, 1985, a Unitarian Universalist minister wrote "to the spiritual assembly of the Bahá’ís of Wilmette, Illinois, to express his feelings of frustration and offense. First he had been invited to read at a World Religion Day service at the Bahá’í House of Worship. Later he was told that his reading selection was not acceptable and that, as he put it in his letter to the Assembly, he must read from “a world scripture such as the Holy Bible, or Koran, etc., or not at all.”
“How would you like,” he wrote, “to be asked to participate in a world religion day and then be told that the host required you to read what he defined to be your scriptures, rather than you being able to read from what you felt represented your holy writings?”"