Dichotomies are useful to a point, but it's a pretty short point. Kind of like how a trowel is useful for starting a hole, but not for creating an entire foundation.
I believe that God gives us tools for understanding people. Psychology has to be from God in its purest form, even though its strongest adherents often lean towards atheism. But tools are just that--instruments for God's purposes, and nothing more. I have been thinking about this sort of thing for several months now, and I firmly believe that any branch of psychology must be used to further love and understand people, not to compartmentalize and reject them.
I was at a grocery store with a friend of mine once. The store was swarming with people, and my friend was of the persuasion that all people are either deep or shallow, and most are shallow. He looked to me sadly and asked, "Doesn't it depress you that nobody here is like us?"
Additionally, my friend Mo just knocked on my door and handed me an invitation to her upcoming wedding. This was a particularly sweet gesture if I stop to think about the fact that we have only hung out once. I met her at the yellow house when I was visiting with Thelma last winter, and I felt an instant connection to her. We sat and talked like we had known each other for years. Since that night we have made plans to spend time together, which have always fallen through. And yet, I feel a closeness to her that I can't explain.
To utilize one way of looking at the world, Mo is an INFP, and so am I. But I wonder, would that connection I feel exist if she were extroverted, or sensing, if she lived by logic or categorized people in her mind? Something complex about why she is the way she is makes her special to me, but it has to be more than just falling on the same side of four dichotomies. It has to be.
Further evidence exists for this by the fact that I feel the exact same connection to a girl who is my almost-complete opposite: an ESFJ. One could argue that she is an atypical ESFJ, but wouldn't it be easier just to accept that people are more than their chemical tendencies? I love this girl because of our eerie similarity that transcends genetics--we are alike because of what has happened to us throughout our lives.
I also love the girl who does my hair. I don't know her personality type, and frankly, I don't care. I can't think of anyone I would rather chill in a salon with and talk about dogs and movies. If we were to take a picture together, it might even look like a dichotomy in color and shape. But it doesn't matter. We're friends. And I felt a connection with her the first time I met her as well. I thought to myself, I want this girl to be my friend. And she makes my hair look good. It was a September miracle.
When I meet someone, I do automatically wonder about their chemical composition and what sort of genetic tendencies they have: which I express via MBTI typology, because it's what I am most familiar with. But that's a starting point the same way that my comment about her cute shoes is starting point for a real conversation. People are far too complex to categorize flawlessly. That almost makes God a finite people factory, when we all know that He has never made a replication in all history. We are shaped by forces we cannot understand. But that doesn't diminish my faith in God or science. It strengthens it.