Is God Infinite?
HOW CAN YOU BE SURE GOD IS INFINITE, ALL-POWERFUL, ALL-KNOWING ETC?
The distance between nothing and something is an infinite distance, so, God who alone can make something out of nothing must necessarily be infinite. All other things get their existence from God; their existence is limited but God's existence is unlimited. God cannot be short of any perfections, because, if He were, He would only have a share of existence, and would not be Existence Itself. Therefore, God is infinite (ie He possesses, in its highest form, every perfection that can exist: goodness, truth, beauty etc).
SO, GOD KNOWS IF I'M GOING TO HEAVEN OR HELL?
Yes. But his knowledge of you ending up in Hell, for example, in no way affects your free willed choice to go there if you commit unrepentant mortal sin. God knows everything, including our future. He knows all of our future free-willed actions but it's us who choose to do them. Our destiny is in our hands in spite of the fact that God knows already what destiny we will choose. Every moment of our life on Earth is an opportunity for gaining merit for Heaven, or, if we so choose, gaining Hell.
WHY CAN'T THERE BE 2 GODS INSTEAD OF ONLY ONE?
Since God is Being Itself, He must be One, for Being Itself is one. If there were two Gods, each would possess but a share of Being, and neither would be identical with Being Itself. If there were two infinite beings, each would possess some perfection which the other did not have (otherwise they would not be distinct), hence neither could be infinite.
* Please note that this text should be read in the context of the whole work and in recognition of the appropriate paragraphs of the Catechism of the Catholic Church highlighted in the index.