There is a lot of give and take on the Internet in general and the Jewish Blogosphere in particular as to whether Hashem exists and whether He really gave the Torah at Har Sinai. Each side tries to prove their position on the matter.
The entire discussion is faulty. The moment one needs proofs for anything then it is not a good sign. We have to be ready to die for Hashem and if we only believe in Him because of proofs then we are in trouble. For every proof there is a counter proof and for every argument there is a counter argument. [As I have pointed out many times - people who don't believe in G-d have yet to offer but ONE SINGLE PROOF to buttress there claim. All they can say is that they have never seen Him. But of course since He is not visible, not seeing Him doesn't prove anything. But they do argue nevertheless and even write books].
Example: I am sitting at a Miami Condo by the pool drinking fresh Orange Juice and enjoying a daf gemara [I am fully clothed]. I hear two guys arguing. One guy says "I can PROVE TO YOU that we are by the pool at a Miami Condo. There is water and a slide. People here are wearing Miami Dolphin caps. Right behind us is a tall building with apartments. There is a sign over there that says "Best Burgers in South Florida".
The other guy argues back "What are you talking about. We are in Honduras. People are wearing Miami Dolphins caps because they came from Miami but are no longer there. "Best Burgers in South Florida"? They are making a movie and are portraying this place as South Florida. The water? It's a bathtub. Etc. etc."
I am sitting there thinking "You guys are a bunch of idiots. I KNOW that I am sitting at the pool at a Condo in Miami. I just KNOW. The whole argument is superfluous."
The Ramban says about Maamad Har Sinai "יהיו עינינו ולבנו שם כל הימים". We are supposed to be CONSTANTLY RELIVING Maamad Har Sinai. If you need a proof then you are not living and experiencing it.
We are supposed to be LIVING Hashem's presence. The only question one may ask is if WE really exist because our existence is not a necessity and could cease at any moment. Hashem IS existence and life [כביכול]. If we have to prove Him we are missing the point.
It is not אנכי ה' אלקיך אשר בראתי את העולם but אנכי ה' אלקיך אשר הוצאתיך מארץ מצרים. Hashem doesn't connect Himself to something that happened before we existed [the creation of the world] but to something we experienced [the Jews who received the Torah were there when we left Egypt with miracles]. We know He is here because we live Him.
We all have weak Emunah because we are not LIVING Hashem as the source of every breath and we see Torah as a nice tradition of thousands of years. If we work on it then we can start viewing Hashem's existence as FOR MORE REAL THAN ANYTHING ELSE and Har Sinai as a daily occurrence.