April 5

We all have a right to our opinions, we are bound to think differently; but a Bahá'í must accept the majority decision of his Assembly, realizing that acceptance and harmony--even if a mistake has been made--are the really important things, and when we serve the Cause properly, in the Bahá'í way, God will right any wrongs done in the end.

...Bahá'ís are not required to vote on an Assembly against their consciences. It is better if they submit to the majority view and make it unanimous. But they are not forced to. What they must do, however, is to abide by the majority decision, as this is what becomes effective. They must not go around undermining the Assembly by saying they disagreed with the majority. In other words, they must put the Cause first and not their own opinions. He (a Spiritual Assembly member) can ask the Assembly to reconsider a matter, but he has no right to force them or create inharmony because they won't change. Unanimous votes are preferable, but certainly cannot be forced upon Assembly members by artificial methods such as are used by other societies. 
(From a letter written on behalf of Shoghi Effendi, 19 October 1947 to an individual believer; The Compilation of Compilations, vol. I, Consultation)