The following is a paper I wrote on my MBTI type for my Self-Awareness in Leadership class.
I have certainly had a long and complicated relationship with the MBTI (Myers-Briggs Type Instrument). For years I tested as (and considered myself to be) an INTJ. Earlier this year, after some careful thought I realized I didn't seem as externally structured and demanding as the INTJ, and that I actually seemed to fit the mold of an INTP better. A few months after that, I further realized that I was in fact an INFJ (albeit a distorted one) and likely had been all along. After all these transitions, I joked that I had made it my new goal to become all 16 types at one point or another; anything seemed possible! To explain my shifts, I had to look into some of the history of the MBTI.
In his 1921 work Psychological Types, the Swiss psychiatrist Carl Jung postulated several theories of personality that persist into the modern MBTI. He saw a high-level divide among people between what he called introverted and extroverted types.  He describes the extroverted type as outward-oriented, with a consciousness focused on the objective, external world: "If a man so thinks, feels, and acts, in a word so lives, as to correspond directly with objective conditions and their claims, whether in a good sense or ill, he is extraverted." Introverts, on the other hand, filter their consciousness through subjective, internal factors; their life is lived not primarily in the external world of objects but in the inner world of thoughts, feelings, and ideas: "Introverted consciousness doubtless views the external conditions, but it selects the subjective determinants as the decisive ones."
Additionally, Jung described four "cognitive functions" that together form the basis of consciousness. These are divided into two perceiving functions, sensing and intuition; and two judging functions, thinking and feeling, which should be familiar to anyone who has been briefed on the MBTI. Jung said that each of these functions could be used in an extroverted (external, object-oriented) or introverted (internal, subject-oriented) way. One of these, the "principal", is the function where "not merely its application is at the disposal of the will, but...at the same time its principle is decisive for the orientation of consciousness." It is the function that forms the foundational bedrock of the consciousness. Besides the principal function, there is another less conscious "auxiliary" function of the opposite judging/perceiving type as the principal.
In the 1940s, Isabel Myers and her mother, Katharine Briggs, crafted a self-reporting instrument to help people discover where they fit in Jung's theory of types. This instrument became the MBTI. Focusing on Jung's pattern of dichotomies between functions, Myers and Briggs used three letter combinations—E/I, S/N, and T/F—to convey a person's general introversion or extroversion, as well as his principal and auxiliary functions. They also added a fourth letter pair, J/P, that indicates whether a person's first extroverted function (not necessarily the principal for introverts) is the judging or the perceiving function.
However, many MBTI tests, books, and websites (including Live Your Calling) don't explain it in this way. Instead of viewing types through the lens of Jung's original system of cognitive functions, with the S/N and T/F pairs giving an individual's main two functions and the other pairs describing how they are manifested, the more common way is to associate certain characteristics with the letter pairs themselves. These distinctions are somewhat accurate for the two middle letter pairs representing functions (though they lose the introverted/extroverted distinction), but rather inaccurate for the first and last pairs. Instead of being associated with how the cognitive functions are used, introversion and extroversion came to describe how people-focused and gregarious you are (or where you get your energy from), and judging and perceiving describe how organized and task-oriented you are. The characteristics associated with a type's four letters are then combined to get the description for that type.
The problem with this approach is that it effectively turns the type descriptions into horoscopes. By defining types by their symptoms and manifestations instead of by their causes (the cognitive functions), a person might find that many different type descriptions sound like them and experience the kind of type confusion that I did. This problem is especially acute for introverted types, since their principal function will be of the opposite J/P type as their type states. (e.g. for an INFJ the first extroverted function is feeling, but the principal function is introverted intuition, a perceiving function) It also conveys the impression that you can only be one of each distinction, e.g. only a thinker or a feeler, whereas in reality everyone does both, albeit to different degrees.
Once I learned to think about types in this way, my own type confusion slowly lifted. As I read some descriptions of the cognitive functions, I realized that introverted intuition seemed to describe me almost exactly in how I thought and processed reality. It had to be my principal function, which already narrowed things down to just two possible types: INFJ and INTJ. (This helps explain why I used to test as INTJ) However, I also realized introverted thinking described me almost as well, as it had formed a tight partnership with my intuition; one generated seemingly impossible ideas and possibilities, the other logically evaluated them and put them into convincing words, a combination that often came in handy on my blog. This helps explain how I identified as an INTP, since introverted thinking is the principal function of the INTP.
But I knew for a fact that I had both of these functions in their introverted form, whereas the INTJ and INTP each only had one (and extroverted the other). But the INFJ had both. And it had something else as its main judging function: extroverted feeling. Since I had always emphatically thought of myself, partially reinforced by the MBTI, as a "thinker" and not a "feeler", this took a while to believe, but eventually it started to make sense. I wasn't interested in ideas merely for the sake of ideas like an INTP, but for the sake of people. And though inwardly I was rigorously logical, outwardly I was more concerned with serving people and making them happy, not with efficiency and logical correctness like an INTJ. (And I was bad at chess, which is virtually the symbol of the INTJ)
As an INFJ, my primary function is my introverted intuition. The result of directing my intuition toward the inner world of thoughts and ideas is that I readily grasp new ideas and am very quick to see possibilities where others don't. I have an intuitive, nonverbal sense of right and wrong, as well as which ideas are correct. I "know" things without being readily able to explain why I know them, and tend to jump to conclusions and then find ways to test and support them. I believe that if there are exceptions to a rule, the rule is too narrow. I see paradoxes and apparently contradictions not as a sign of fallacious thinking but as a challenge, a contribution for a higher, overarching "theory of everything". I am always looking at problems and ideas from multiple angles, trying to understand every side in a conversation at once.
I am used to combining this intuition with thinking, which has helped me become the amateur theologian that I am, trying to make sense of Christianity, the Bible, and conversations on faith. But according to my description thinking is only the tertiary function, whereas feeling is the auxiliary function. And so I have been learning to applying my insights more directly to people. This has multiple implications for working in teams. INFJs value harmony, and I am certainly no exception; I would love it if everyone could just get along, or at least disagree nicely and constructively with no raging tempers or hurt feelings. To this end, my intuition helps me in seeing both sides of a conflict, while my feeling function helps me to act as a mediator. At times I can be more interested in simply making sure a team is getting along, maximizing the potential of others, than in contributing to the end goal.
On a more individual level, the INFJ's combination of intuition and feeling makes them very good at picking up on nonverbal cues and emotions. If someone is feeling "off", I can usually tell. (The challenge is actually doing something about it) When teaching Sunday school, I tend to gravitate towards the kids who are alone or off by themselves; as a child I often felt like an outcast and so I am drawn toward other outcasts. This can again be useful for building unity on a team. Also, INFJs tend to be perfectionists who hold themselves to very high standards. The wishes and expectations of others hold a very high value for me, to the point where I sometimes idolize them. For this reason I am very keen to carry out what is expected of me by others, not out of an innate sense of duty like the ISTJ but because I care about people and am anxious to please them.
On the other hand, the INFJ's reliance on intuition above all else can also get them into trouble. When someone disagrees with me or my values, my first response is to assume that the conflict arises from a limitation of perspective and look for a way to reconcile our apparently clashing views by explaining how they can both be true. If I am unable to do this, though, or if the other person doesn't accept my explanation, I will stubbornly cling to my intuition even in the presence of opposing arguments. I believe strongly that I am right, and the only reason this confidence in my ideas doesn't get me into more trouble is because I usually keep it to myself and try to avoid saying things to others that I can't support.
My introversion can also be a weakness in a team or relationship. Though I value deep, close relationships, I am also very private and value time spent alone. This means that I am best on a team when I can still work relatively independently and present only my finished work to teammates. If I am forced to work more closely with other people, conflict can arise (I always dreaded group projects in school). It also makes me slow to warm up to and trust people; I probably come off as distant or tuned-out to most people except those who know me well. Because I am so slow to form new relationships, I treasure the ones I have.
Some "natural" spiritual gifts for an INFJ might be service, mercy, or discernment, but more than these I tend to use knowledge and giving. For me knowledge is not simply the timely and helpful remembrance of facts, but more a natural talent for navigating the world of truths and ideas behind these facts. My inclination to help and please people motivates me to turn this gift to the service of others instead of just endlessly indulging my curiosity. Likewise, it is mostly my desire to help people however I can that lies behind my gift of giving; I recognize the resources God has given me, see ways to contribute them for the good of others, and then do so. I tend to be very devoted to those I care about, which makes it easy to give parts of myself to ministry partnerships.