In Cult of Karna theology, the human soul is like a lens or a crystal that scatters the light of God (i.e. Truth). Taken as a metaphor, this illustrates how one 'polishes' themselves to better 'reflect' the truth of god. In other words, if you are pure of heart, your appearance and actions will be closer to Karna's will. If you carry darkness in your heart, however, you cannot receive god's blessings.
Those that worship Speed follow a similar vein, except that the truth of Speed is altogether unlike the truth of Karna. While Karna is seen as a reliable, overt, dependable force for good, Speed is viewed more as a covert and unpredictable god. The two collaborate and compete in various ways, but neither accepts ambivalence from their followers. Only royalty are known to court both.
There are those that reject both, as well. The Tempest's Elect are a radical example of this.