Paul talks about allowing different believers to hold different views, "without passing judgment on disputable matters." The Western/American church has always been horrible at this, which is why we have so many denominations.
I think this problem arises from 2 flawed assumptions: 1) That we are capable of fully understanding biblical doctrine; and 2) That if we disagree, one of us must be WRONG. Let's take these one at a time, although they are related.
The idea that we can comprehend the thoughts of God is ludicrous. I occassionally get to be Moses, seeing just a glimpse of His glory. But I can't figure out how to make sense of the Trinity, to understand the mechanics of Creation or the Incarnation, to rightly balance love and justice, grace and the law, sovreignty and free will. And I don't think you can, either -- no one this side of the veil can.
So you and I disagree over exactly what happens in Communion, or how prayer works, or whether Christians should dance or play cards. Does that mean that one of us is right and one of us is wrong, and we can not fellowship? Here's the secret: Related to point number one, any time we disagree over doctrine, we are almost certainly BOTH wrong.