The speaker describes anger as something worn on purpose, like a creed or a set of beliefs slipped on "to see how it is." That phrasing suggests experiment rather than conviction. The rage is "ready," always at hand, but it may not be entirely real. The images that follow are bare and severe: a thin whip, a rock, a candle on the ground. They feel like the props of a stripped-down ritual, part penance, part punishment, with almost nothing to comfort the person performing it.
The last two lines turn the poem inward. Without wonder, without any sense of awe or openness, the speaker is left with anger as a substitute. Calling it a "lie" is a quiet admission that the rage is a pose, and that keeping it up hurts. The mood is austere, self-aware, and a little sad. The title, "Piety," makes the point sharper: the speaker is devout, but toward the wrong thing.