So what does it mean according to Merriam Webster:
1: having infinite awareness, understanding, and insight
2: possessed of universal or complete knowledge
According to the philosophers at Stanford:
Omniscience is the property of having complete or maximal knowledge.
According to Christian Apologetics and Research Ministry:
Omniscience is an attribute of God alone. It is the quality of having all knowledge (Isaiah 40:14). God knows all things possible as well as actual because he has ordained whatsover will come to pass according to the counsel of his will (Eph. 1:11).
So I originally though that omniscient meant all knowing, and from the definitions I was right. So does god then know what will happen in the future if god knows everything? The answer must be yes, as if god has all knowledge then surely god must know the future. If god does not know the future then god cannot have all knowledge, as the future determines what knowledge we humans will learn.
At this point a theist can say that does not mean that god does not have the knowledge as god can still have this knowledge, but we as humans do not have it yet. I disagree with this, as knowledge means who did what as well. So by default god must know who will discover this knowledge. For example if say E=mc^2, everyone immediately thinks Einstein. That is knowledge, so god must know this and herein lies the problem.
Sorry theists if god is omniscient there is no longer any free will. If god knows everything then there can be no free will, as god already knows what will happen so our choices are already made before we make them. This is a big problem for theists as god then has already decided who will burn in hell. In my humble opinion this makes god a very bad deity.