Technically speaking, nothing can be 100% proven. We consider something 'proven' when the evidence favors it more than it opposes it. So the question is not 'can God be proven to exist?', but 'does the evidence favor the existence of God more than it favors the idea that there is no God?'. When dealing with the question of God's existence, we would not only look at the scientific evidence (which alone, I believe, strongly favors God's existence), but also the philosophical and spiritual evidence as well. For example, if someone were to ask you whether or not love existed, I doubt you would deal only with the scientific evidence, but would deal with the questions of why people risk their lives to save others, or why a couple will stay together for many years, forsaking all others. The only way that we can absolutely know something to be true is to experience it ourselves. For example, if you've never been to Singapore, believing in the existence of Singapore can only be done on faith. You can see it on maps, read about Singapore in books, or talk to people who claim to have been there, but you would have to have faith that these maps, books, and people are truthful. Only once you've gone to Singapore can you know, without relying on faith, that Singapore exists. Yet most of us believe, by faith, that Singapore exists. The only way to know, for sure, that God exists is to make the attempt to experience God in your life. This can be done through prayer, through reading the Bible and applying it to your life, and through going to church.