As regards the other religions in the texts of Baha’u’llah and in the books of the loved ones like the book of Mirza Abu al-Fadl, as well as my writings, they have explicitly mentioned his holiness Zoroaster, his holiness Buddha, Brahma, and Confucius. In the beginning, the foundation of his holiness Zoroaster and his holiness Buddha very much agreed, but afterwards there was distortion and change.
Methinks thou hast not seen the tablets and books that have been written about this. If thou art able to obtain the book published by Mirza Abu al-Fadl, it is sufficient. Be thou satisfied that the teachings of Baha’u’llah are universal teachings and that thou art aided by the potency of the Word of God, the breaths of the Holy Spirit, and a heavenly power.
At most, thou hast seen the published writings of his holiness Baha’u’llah. Published tablets relative to unpublished tablets are very partial. The foundations of the divine religions are one. That foundation shall become universal through the power of his holiness Baha’u’llah.
Abdu’l-Baha, Makatib Abdu’l-Baha 3:378-9; Amr va Khalq 2:71.