The opening argument has great merit based on logic as we know it today. Connecting a "higher power" or "greater power" with the Christian God as it is defined in the Bible is devoid of all logic.
If your point is Christians cannot prove God, as they know the word, exists. But that is not terribly satisfying from the standpoint of answering the question, "Then what is this this higher power, and how can we understand it better?"
This is a deep subject, but let me just breach the surface by saying that scientists cannot offer an explanation of what causes gravity, why our universe continues to expand at a ever rapid pace (against all laws of gravity), or what is this "dark matter" that has the property of matter but cannot be seen or detected with any instruments.
My point is that mankind circa 2008 is still in the stone age regarding understanding physics of the universe. We cannot hope to guess what is creating order in the universe. Therefore we cannot hope to understand what powers this "higher power" really possesses. Is it a purely physical thing or event, such as the big bang, which set the universe in motion... then simply vanished? Or is this power capable of influencing the lives of individual humans.
Our minuscule knowledge of physics can strongly prove that particles called electrons exist... why then do not particles called deitons exist? That is, a mechanism acting within us that is perhaps responding to an external aether which may be the dimension where the universal higher power exists... similar to dark matter.
The possibilities here are endless, and your conclusion that Christians (or any other religion) indeed has the correct answer is 100% unsupportable. I am intrigued, however, but the innate desire for human beings to believe in a God. It suggests that some power does exist in our lives that can influence our actions. That fact alone is a great curiosity and is something that we must contend with, even if our conclusion is "I do not have sufficient information to know the correct answer."
