One of the lesser martial arts (word origin: the Greek word for "defend"), or a spiritual-hardware abstraction layer. Tends to work best when one isn't literally put in a position to defend - it's much more edifying when the audience is receptive, either because they're somewhat converted or because they're genuinely curious. Flat-out mutual antagonism often results in an ivory tower of babble, with the time better spent in prayer or frying an omelet. Grace Happens. Hold the onions.