To be a Baha'i kind of means you don't believe certain things that are major beliefs in the other religions. What are the reasons Baha'is don't? Then, coming from believing in another religion, that person has reasons why they don't believe in the Baha'i Faith. Can either one disregard those reasons? It's not complaining. It's have religious belief that are different and contradictory. And each believes their religion is the one the is correct.
Can a Baha'i really stop caring about those differences and accept the beliefs and practices of the other religions? I don't think "true believers" in any religion can do that. It goes against what they believe is true. Can a Fundy Christian put aside their beliefs about Jesus, that he rose from the dead and is the only was a person can have their sins forgiven, and a big one, that he is God incarnate? Probably not.
But can a Baha'i put aside their belief that Baha'u'llah is the true manifestation for today? That Jesus is just one of many manifestations and that his teachings have long been replaced by the teachings of Islam and the Baha'i Faith. Unless a person is super liberal about doctrinal beliefs, then I don't think so.
So, what's more important to Baha'is, being strong on the belief that Baha'u'llah is a manifestation of God, and his teachings are the only way to bring peace and unity to the world. Or putting those beliefs on the back burner for the sake of being able to find those things that you, as a person, has in common with Fundy Christians, or Muslims or Hindus or anyone else, including Atheists?
Maybe you can. Maybe you try to. But we're here on a debate forum to question these different beliefs. And then there is the problem of the "hidden" agenda... Once a Baha'i or Christian or whomever finds the commonality with the other person, then what? Do they then, slowly, start "guiding" them to the "truth", the Baha'i truth?
I've seen it done by Baha'is and Christians. Make friends with someone, get them to know you and trust you, then invite them to a fireside or Bible study. Or give them a pamphlet to read. But does the Baha'i or Christian ever intend to seriously consider the beliefs of the other person? No, the Baha'i and Christian know they have the truth and are only trying to guide a lost soul to that truth.