The two people who disagree about the monster agree about all the other animals. God, however, is not merely 'one more thing.' The person who believes in God and the person who does not believe in God do not merely disagree about God. They disagree about the very character of the universe. The believer is convinced that each and every thing exists because of God and God's creative activity. The unbeliever is convinced that natural objects exist 'on their own,' without any ultimate reason or purpose for being. In this situation there are no neutral 'safe' facts all parties are agreed on, with one party believing some additional 'risky facts.' Rather, each side puts forward a certain set of facts and denies its opponent's alleged facts. There is risk on both sides. (C. Stephen Evans, Why Believe? Reason and Mystery as Pointers to God, p.22)
See here for an expanded version of this argument with reference to Russell's 'celestial teapot.' This is similar to a point I made in a post a while back, on the question whether the theist bears the burden of defending the addition of 'metaphysical baggage' to our cosmic account:
I was thinking recently about why atheists so often refer to God as an 'unnecessary hypothesis'. Of course I can understand the intellectual appeal of such a rhetorical strategy, as it provides atheism with a rational foundation. My question was more how is it that they are able to use this strategy with such ease and assurance? It occured to me that it stems from a particular way that atheists (and many theists) construe the relationship between naturalism and theism, encapsulated in the title: theism is basically the same as naturalism, EXCEPT there's an extra being called God who intervenes in nature and ensures an afterlife and so on. On this view, God may do some metaphysical 'work' in the form of ensuring that the wrongs in this life will be righted in the next, or serving as the recipient of prayers and the focus of spirituality, but other than that it is assumed that naturalists have access to the same moral and intellectual resources as theists: naturalists can do good science, write up ethical theories and find life just as meaningful as the theist. When naturalism and theism are so construed, especially with the invocation of science as a source of explanations for why things are the way they are, it is only natural that theism should be seen to carry unnecessary metaphysical baggage in the form of the God hypothesis. When arguments are put forward for and against the existence of God, this view is tacitly assumed: God's ontological and explanatory status is judged based on the framework of just about everything else that we take for granted.
In a recent and provocative article (in the edited volume How Successful is Naturalism?), however, philosopher Nancey Murphy persuasively argues that both theism and naturalism represent competing 'traditions' in the sense put forward by Alasdair MacIntyre: competing, complete accounts of the world and the human condition, often (though not always) based on the interpretation of certain privileged texts, and which must be judged not by the isolated deductive arguments for the reality of their ontological postulates, but by the extent to which they make the best sense of human experience as a whole, their progressiveness and their ability to overcome various epistemological crises which occur at various points in the development of each tradition. She gives several examples of theistic crises, including natural evil, divine action and the diversity of religions and also sketches two naturalistic crises: the persistence of religion despite its alleged refutation due to the pioneering efforts of Hume and the 'masters of suspicion', Freud, Marx and Nietzche, and naturalism's inability to ground a proper normative account of ethics.
There is not space here to evaluate her account of these crises, but I think it is extremely important to be clear exactly how to formulate the conflict between theism and naturalism. It is definitely NOT the case that theism simply carries an extra metaphysical burden, i.e. the 'God hypothesis', which it must defend with deductive arguments. Rather, both theism and naturalism try to offer integrated accounts of the origin of existence, human nature and morality and must be judged at the broader level of these accounts. Naturalists often assume that they have access to intellectual and moral resources which in fact they should really have to argue for rigorously (all too often in response to challenges to naturalism I hear the same lazy reply: "but why can't a naturalist simply assume X?" or "I see no reason why I should have to defend myself on this point").