"The assumption behind the Enneagram is that underlying every thing we do is one major temptation that is particular to us. And until we see it for what it is, we will inevitably give in to this temptation and live in bondage to it.
"The core sins identified by the Enneagram are each associated with a core need. The needs are basic human needs, such as a need for love, for security or for perfection. The sin consists in making these something of ultimate value–that is, making them into God.
“Fives need knowledge, long for fulfillment, and are tempted by greed, stinginess and critical detachment. Thomas, the so-called doubting disciple, fits this pattern.”
Benner, David G. The Gift of Being Yourself. Expanded ed. Downers Grove, Ill: IVP Books, 2015, p. 64.
I/we need to remember that the value of tools like the Enneagram is not that it describes our strong points or valuable assets, but that it points out our weaknesses, our core sin. In this tool the core sin is connected with a need I have (because of my upbringing or whatever). What’s sinful is when I turn that need into something more important to myself than God is. The need – in my case, a need for knowledge – is fine, okay, good, even admirable when met; but it has to be unbent. The need isn’t more important than my relationship with God. Meeting that need can be done in ways that honor the relationship with God or dishonor it. Our choice.
(I also remember one of my Easter season sermons in which I called “Doubting Thomas” the patron saint of scientists and other researchers. He was not so much a doubter. He was just, you could say, using his God-given intellect to gather evidence and then once he had it, he was convinced.)