From the EthicalAtheist.com web page "Questions for God" [1]:
Why don't you show yourself? You supposedly made us and want us to believe in you, right? Why the big mystery? You're also omnipresent, right? Why don't you show yourself to all of us at once and have a personal discussion with us? You can pick the date and time, we'll all stop what we are doing, I'm sure.
Why doesn't God dance when you want him to, and to the tune of your choosing? Why doesn't God put on some righteous cosmic magic show to convince you that he exists? Allow me to submit what I think is a far more pertinent question: "What would be the point?"
Imagine for a moment that God does your bidding. Whatever it would take to convince you that he exists, let's assume for the sake of argument that he produced it. Presto, you affirm that indeed God exists.
Now what?
So you now believe he exists. Well that's fantastic but, if I may be so bold, "So what?" What does this profit you? Are you so ignorant and out of touch that you think God will love you and accept you just because you assent intellectually to his existence? Are you so presumptuous as to dismiss with a wave of the hand your tremendous debt of moral culpability and (even worse) God's righteousness and sovereignty? Is God supposed to be so overwhelmed with gratitude for your cognitive approbation that he will just ignore the holy demands of justice? It's great that you now believe he exists. But so what? Will you now obey his commands? Do you throw away your ethics and other philosophical commitments and subject yourself fully to the will of God and what he demands?
No.
Why doesn't he show himself? Why doesn't he put on a cosmic magic show to convince atheists he exists? Because it would be pointless. It profits him nothing. It profits the atheist nothing. The atheist's intellectual assent is barren and impotent. For Satan himself believes that God exists, and he will believe that all the way to hell. The problem is not in the atheist's head but in his heart. When it comes to a relationship with God, the atheist's problem is not an intellectual one, but a moral one—on several different fronts.
As Rabbi Harold Kushner so eloquently put the matter:
Paul, whose conversation with me ultimately flowered into this book [2], assured me that while he did not believe in religion, he believed in God. I asked him what he meant by that, and he told me that when he contemplates the beauty and intricacy of the world, he has to believe that God exists. That’s very nice, I told him, and I’m sure God appreciates your vote of confidence. But for the religious mind and soul, the issue has never been the existence of God but the importance of God, the difference that God makes in the way we live. To believe that God exists the way that you believe the South Pole exists, though you have never seen either one, to believe in the reality of God the way you believe in the Pythagorean theorem as an accurate abstract statement that does not really affect your daily life, is not a religious stance. A God who exists but does not matter, who does not make a difference in the way you live, might as well not exist.