One of the difficulties I had in the past was wondering why God would not appear to each of us individually once to say, basically, "hey, I exist." After all He's all-powerful. But it occurred to me recently how even a personal appearance, as life-changing as it might be, could eventually be seen as inadequate. If everyone got one visit from God then we'd complain: "why don't You appear every moment to me?" Which is really calling on Him to remove his gift of freedom, which would be to remove our dignity, which make us no longer made in the image and likeness of God.