We believe all the Manifestations of God whether it be Baha’u’llah, Muhammad, Krishna, Jesus, Buddha, Moses, Christ or , Zoroaster are all infallible. This is our basic belief.
Infallibility
Regarding your Bahá'í friend who does not fully understand the infallibility of the Manifestation of God: You should influence that person to study the matter more deeply, and to realize that the whole theory of Divine Revelation rests on the infallibility of the Prophet, be He Christ, Muhammad, Bahá'u'lláh, or one of the others. If they are not infallible, then They are not Divine, and thus lose that essential link with God which, we believe, is the bond that educates men and causes all human progress."
(From a letter written on behalf of the Guardian to an individual believer, January 11, 1942)