Okay...first to the idea of omnipotence. Many Christians say and believe that this means God can do anything. On the other hand, we also say that God is completely good, thus, God cannot sin. Wait a minute, isn't there a contradiction here? They can't both be right, can they? Well, no, they can't both be right, but since one of your premises is wrong, it doesn't really mean anything. Omnipotent means all powerful, and another way of saying it is that there is nothing God is not powerful enough to do. For a different example, we know that God could not make a round square. Why? By definition. If it's round, it can be one of many shapes, but it can't be a square. So, while it's true that God can break many of the laws of our universe(like Puppychow's example of Lazarus, since He can take the physical body and heal it, as well as take the spiritual essence, AKA soul, from heaven and return it to the body, thereby resurrecting someone) He cannot change the nature of some things. The idea behind them. Does that make sense?