Belief in the Old Testament precludes belief in the New Testament or Koran

I apologize if this seems rushed; my brother is getting married, and I am extremely busy. Proof #1 When I stated that "whether or not God spoke is almost irrelevant", I did not mean that a lack of that meant there was only natural phenomena. I meant to say that God's presence and approval were apparent to the whole nation, and that is an unparalleled standard in my opinion. Nonetheless, if God's voice is integral to establish a non duplicated standard in my opponents eyes, I still stand by those proofs, and my opponent must refute them. Even so, I will address his points. My opponent claims that supernatural events happened around other prophets in Old Testament, and that the standard of revelation should be measured with them. There are two issues with this, which miss the point of my original argument. 1)The fact that subsequent prophets may not have had the same standard of revelation is irrelevant. Prophets don't need miracles to prove themselves. The bible says they can merely correctly predict the future, or something similar. In fact, they can be merely confirmed by a different confirmed prophet. The issue is that no subsequent prophet attempted to change the commandments, because only something with that original standard can do that. In other words, a perfectly valid prophet can still not have the authority to change the commandments. Just because the people accepted them does not mean they are standard to judge Jesus and Mohamed, who changed the commandments. The point is that just because those prophets gave commands or messages, does not mean they gave commandments. 2)Even if the bible did claim similar miracles to the prophets, or Jesus or Mohamed or anyone else, it still would not be a sufficient standard. The point is not that miracles took place; it's that miracles took place in front of the entire nation. This was so no one could doubt their validity. As I've stated, it is impossible to create a lie of that nature. If God delivered his commandments in a way that no one could doubt, then clearly, He would want- and need- to do so again. He would do it to only the people present in king's courts, or any small crowd, or individual. In short, God set up a standard for giving commandments- by showing his approval in front of the whole nation- that has never been duplicated. If new commandment was to be given, or the old ones revoked, a similar event would need to take place, which never happened. Proof #2 "See that you do all I command you; do not add to it or take away from it." This verse bears no exceptions. Not to prophets, who are bound to each and every law just as much as the rest of the Israel. Note, also, that commands and commandments are not the same thing. A commandment is a rule. "Don't murder", "Honor your mother and father" etc. A command is specific instruction. "Appoint Saul king over Israel" "go to war with the Philistines" etc. Any prophet who gives a commandment is in violation of this, and no Old Testament prophet did. Moses himself only finished telling over the commandments because the people were too frightened by God and asked him to. And I don't see how this verse should literally end the bible; it is in infinitive tense ("all I command you) not past (commanded). As far as Jesus and Mohammad go, the both violated this verse, and the verses about rebelling against the commandments [1] [2]. This being the case, they invalidated anything they might say. The nature of the system of commandments is that its irrevocable by any mortal man (or someone bearing the appearance of one.) [1]http://www.trusting-in-jesus.com... [2]http://en.wikipedia.org...