Ant started it off. Well ok, not the whole thing - the Americans probably did that. Oh no, the Greeks actually, with their four temperaments. Personality testing though. I've some reservations:
:-? personality tests which are specific enough to be worth doing don't tell you much that you don't know already, so aren't worth doing (eg they tell you that you're the kind of person who prefers to read a book rather than go to a party - well I figured that out since age 4!). But of course they're still interesting because we're all interested in ourselves and interested in understanding others, so on to my real concerns...
:-? results are frequently used to explain actions and it is therefore a temptation to use them to excuse actions: "I'm sorry BUT it was my ... side coming through" as if personality is a provision for sin. (e.g. "Well I'm sorry it hurt you but that's who I am: I say things straight." Rather than, "I'm sorry I hurt you;that was wrong of me. I'll try to understand more next time to help me explain what I think without hurting you.") The other side of this coin is the temptation to use them to dismiss others' thoughts or actions: "You're only saying that because you're a ... personality!"
:-? results lend to the idea that personality does not change. They don't acknowledge that some tendencies in each personality are good and some are sinful. They don't acknowledge the role of character, which can be sanctified by the Holy Spirit as he gives grace to continue to bring about the obedience of faith - this surely interplays with personality. In other words, having found out my personality type, there is a temptation to not seek to be transformed by the renewing of my mind and offer my whole self as a living sacrifice, but only offer myself as a sacrifice within the bounds which I imagine myself to be capable of personality-wise. For example, an introvert such as myself thinks, "There's such&such a project on which would be great to go to, to encourage/invite/etc, but it's not for me - I'd hate it all evening; God doesn't require me to go against how he's made me: I'll not go." Or, "I'm the thinking/judging type - I'm not like this wishy-washy feelings-oriented crowd. I tell it straight, that's the way God's made me" rather than seeking to consider what people feel about what I'm saying at the same time, in order to truly communicate in love.
:-? Personality types only acknowledge what is natural for us, not what we're working on. They're also quite extreme. So do you either act with someone on the basis of truth and facts without regard for their feelings or do you disregard truth and act on the basis of how it will make them feel? Well as Christians do we not try to 'speak the truth in love'?? We try to do both! But this test would ask,"But what is most NATURAL to you? - go with that!" That is actually what a careers person said to me when I posed that problem in response to this issue. That's rubbish. As Christians we don't go with the extreme that comes most naturally to us. We seek to be more like Jesus, seek the Holy Spirit to transform our sinful tendencies and build us up in where we are weak.
For those reasons, I really don't think that personality tests are that useful. They might be personally helpful for example in helping an individual think through what kind of job he might like... perhaps. Certainly they're not easily avoidable as employers everywhere are into the trend. But for Christian discipleship? No thanks. Maybe what we need is more genuine communication. None of us wants the others to categorise them into little personality boxes. But we don't need this; we do need to speak to each other honestly and take time about it, not so that we can dismiss or excuse, but so that we can speak the truth in love to build each other up.
But perhaps I'm just posting that because I'm an INTJ.