Discussing
Hearing the Hound of Heaven in Oz the Great and Powerful

You're right, Josh: the "throwaway" moment when Oz fears passing through the protective bubble is a pivotal scene in the whole film. For the very first time, he publicly (if less than explicitly) confesses his sin. And maybe that's the first step for all of us...acknowledging our own frailty. Maybe this was Oz's way of surrendering, or saying, in the words of the Psalmist, "I have no good apart from You" (16:2).

At any rate, I find it revealing that Glinda turns out in the very next scene to have known Oz's secrets all along (much as the Lord knows us intimately), yet seems to have been simply waiting for Oz to own up to himself. She then insists that Oz will be useful to the land in SPITE of his weaknesses (much as our Lord uses us right where we are when we surrender to Him.)