Most of the lines are four measures long, and with three beats in each measure, this adds up to twelve, which is also a significant number in Christianity (the twelve tribes of Israel and the twelve apostles, for example). This doesn't seem to be as important as the threes, however.
That one E major chord coincides with "a whole world of" in the line "They say I'm missing a whole world of fun." Because of the accidental in E major (G#) and because the chord's root is something other than the tonic (D), subdominant (G), or dominant (A), there's a musical illustration of the incongruity between this world of sin (the "things I despise") and the Christian life.
Appropriately, the phrase "walk in the light" comes from 1 John 1:7: "But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin."
