The reason there were miracles in the past is because at some point in the future we developed time travel. This, along with the bad conditions in the world, led us to go back in time and use future technology to perform what looked like miracles to the people back then. Our goal was to make the future a better place to live by making people believe in and fear god. Along with this we planted the various religious books, the Bible the Koran etc... The unfortunate side effect was that once people started to worship god no one believed time travel was possible so it was never invented. And that is why we no longer see miracles in our time.
*This post is true because it written in this post.