Today the Baha'i teaching of oneness of humankind is widely accepted, but in the early 1900s it was a difficult concept to convey or put into practice. Abdu'l-Baha made this principle a centerpiece of his talks and actions in the West.
published in Lights of Irfan, 14, pages 289-320 Wilmette, IL: Haj Mehdi Armand Colloquium, 2013
Abstract: The central teaching of the Bahá'í Faith is the oneness of humankind. Although wholly associated with the Bahá'í Faith today, it was a very difficult concept for Bahá'ís in earlier times to put into practice in their personal lives. As `Abdu'l-Bahá travelled in the West in 1911 and again in 1912-13, He not only spoke extensively about this principle in numerous meetings but demonstrated its meaning in practical ways and challenged His followers to take up the fight against racism within themselves and their society. This paper looks at `Abdu'l-Bahá's elucidation of the principle of the oneness of humankind in His talks in the West, primarily in the United States, and through His own actions