He stressed that Baha'is of Christian background should accept these principles concerning Islam

While walking with us in the gardens of the Shrine during our second meeting with him, Shoghi Effendi spoke of Muhammad, Whose station was lofty and great, as the recipient of a Divine Revelation. He returned to this theme on a later occasion, saying that the believers should be aware, and believe, that Islam is the origin of the Baha'i Faith, that the Qur'an is the Word of God and that the Imams were infallible. Their station was very sacred and exalted, particularly that of Imam Husayn (the third Imam, titled the King of Martyrs). As to the traditions of Islam, those which are quoted in the Writings are authentic. He stressed that Baha'is of Christian background should accept these principles concerning Islam, just as those of Jewish or Zoroastrian background should accept Christ as the Word of God and His utterances in the New Testament as authentic.

- Hand of the Cause, Ali-Akbar Furutan (‘The Story of My Heart')

http://bahaistories.blogspot.com/2017/04/the-furutans-first-pilgrimage-during-ww.html