The logic goes like this. Jesus said we can judge a tree by its fruits. When people are excluded by or express personal frustration at a point of doctrine, we should be suspicious of that doctrine because of the bad fruit it is beginning to bear. On the flip side, we should evaluate doctrines for their truthfulness in large part by whether or not they bear good fruit–that is, by whether or not, by believing them, we become more friendly, more inclusive, and more ingratiating to the people around us.
But C.S. Lewis has some problems with this idea. And in his essay "Man Or Rabbit," he explains why this sort of approach of doctrine isn't a respectable one:
One of the things that distinguishes man from the other animals is that he wants to know things, wants to find out what reality is like, simply for the sake of knowing. When that desire is completely quenched in anyone, I think he has become something less than human. As a matter of fact, I don’t think any of you have really lost that desire. More probably, foolish preachers, by always telling you how much Christianity will help you and how good it is for society, have actually led you to forget that Christianity is not a patent medicine.
Christianity claims to give an account of facts–to tell you what the real universe is like. Its account of the universe may be true, or it may not, and once the question is really before you, then your natural inquisitiveness must make you want to know the answer. If Christianity is untrue, then no honest man will want to believe it, however helpful it might be; if it is true, every honest man will want to believe it, even if it gives him no help at all. [God in the Dock, p.108-109]
When we're looking at doctrine, our ultimate question cannot be, "Is this helping us?" Rather our ultimate question must be, "Is this true?" That means at least two things.
First, it means that our doctrines of Christian belief are not meant primarily to help us live and work well with others on this earth, but to help us know and be known by God. We should indeed strive to live at peace with all men, and our love for other Christians is a sure mark of our Christianity. But this is much different from saying the essence of our Christianity is our relationships with other humans. Christianity is news from God first, before it is helpful to us.
Second, it means that we simply cannot judge a doctrine's truthfulness by how seemingly helpful it is in our life. Truthfulness and helpfulness are not the same thing. To conflate the two is really a Darwinistic way of looking at Christianity, as if the "strong" doctrines that further social harmony are meant to survive and the "weak" doctrines that are antiquated or unpopular need to die off. The Bible is clear on many points of doctrine that our neighbors may not admire us for believing, or that may not actually help us win favor and friendship (even inside the church!)
But as Lewis reminded us, truth is valuable apart from its helpfulness. Truth is not merely a means to an end but an end itself. "I am the Way, the Truth, and the Life." (John 14:6)