Throughout the history of philosophy, many arguments about the existence of God have been proposed. Some have defended theism, others atheism, and still others agnosticism. But while philosophers have been busy trying to determine whether or not God exists, they have often neglected to ask: “What difference would – or does – God’s existence make to the overall value of the world?” This question is not about the putative advantages or disadvantages of some individual or society having religious beliefs or engaging in religious practices. It is, instead, a question about the axiological consequences of theism. This research project will systematically investigate various answers that might be given to this profoundly important question. Some say that God’s existence would make the world far better than it would otherwise be. But this is not the only possible view. Some have said that God’s existence would make the world far worse than it would otherwise be, and still other answers could be given. For example, one could hold that God’s existence would make the world neither far better nor far worse, or that the effects of God’s existence on the value of the world simply cannot be determined. This project aims to identify and evaluate arguments for and against all the major positions on this issue. In so doing, this project will also address the following question: “How can we tell what difference God’s existence would – or does – make to the overall value of the world?” This project presupposes neither theism, atheism, nor agnosticism.