So Baha'is are perfectly fine with other religions having beliefs that the Baha'i Faith says are wrong? But, I thought of another question for you that relates more to this OP also. The way Baha'is have presented Progressive Revelation is that the new message is needed for the advancement of civilization. The old religions and their old laws have been replaced with better, more up to date information from God. So, up to the coming of the Baha'i Faith, Islam was the most current message from God, do Baha'is believe all people of all the other religions should have recognized Muhammad and followed his teachings? If "yes", then, even if their old religion believed in monogamy, those "pure hearted ones" that recognized the truth of Muhammad's message, should have taken multiple wives?Muhammad said it in the Quran.
'There is no compulsion in Religion.' As such one respects the right for people to choose their own path, it is a God given right.
What can be mutually shared is virtues that enable us to exist together harmoniously.