The experience of creepiness is, at its most fundamental, the experience of an excessive, asymmetrical demand — someone is demanding something of us that we cannot and do not want to reciprocate.
The privileged field of creepiness is of course sexuality. I think that most of us, were we to learn that someone was attracted to us, would be at least mildly flattered, on one condition: that the person is in our “range.” If the person is, for whatever reason, very unattractive or even repulsive to us, then we experience that expression of desire as creepy. (I suspect that the same might be true if we learn that a person who is much, much more attractive than us is “into” us — we would assume that they have some mysterious, creepy agenda, that they have attached excessive importance to some other feature.)
This works in other fields, too. We might be creeped out by the person who is way more into a topic than us, who has been absolutely starved for someone to discuss it with and latches onto us as soon as we show the slightest knowledge or interest. We can all probably think of other examples along these lines. The unifying feature is the sense of being violated by the excessiveness of the other’s desire, of having been made the object of a desire with which one cannot subjectively identify. (And this accounts for the fact that we can find situations creepy in which we are not actually implicated — for instance, being creeped out by the displays of affection of a very unattractive couple, or by an Andy Kaufman comedy routine where his desire is obviously extremely intense but at the same time opaque.)
While creepiness may seem to be an inherent trait of the individual creep, it is actually socially mediated. (A book on creepiness was, after all, projected as completing a trilogy with Awkwardness and Sociopaths — I had to find my social element eventually!) The creepy person fundamentally does not know his or her place in the social hierarchy. The nerd might be allowed to admire the popular girl as a fantasy object, but he cannot proceed on the assumption that the pairing could actually happen. Admiring from afar is a way of acknowledging his place, whereas pursuing her concretely disregards the appropriate social hierarchy and is therefore creepy. On a more individual level, it’s creepy for someone to act like an intimate friend or close intellectual comrade without “putting in the time” — they haven’t worked their way up to that level, they don’t acknowledge your own personal hierarchy of friendship.
Hence the redemptive element in creepiness might be its ability, not so much to invert as to simply disregard social hierarchy — to flatten out a plane for a democracy of desire. For the creep, anything is possible, no desire must be preemptively renounced. Hence, perhaps, the sense that the Holy Spirit is creepy.