The claim that something is, is to claim that something can be. To say that there is an is, is to say that it is possible to exist. Therefore in the process of saying the possible one says the inevitable. For, conversely, if something is possible to exist, it must be possible to exist. Since the converse holds true, it is impossible to differentiate between the possible and the inevitable. They are the same thing. Since it is impossible for man to experience anything which is impossible to experience, he only experiences the possible. Thus the possible is inevitable; the inevitable, possible.
The possible-inevitable and the inevitably-possible are the same thing, namely man's solipsistic nature. Solipsism is man's inability to distinguish his memory or present senses from an independent-external reality. Since man only experiences that which he experiences, he has, by nature, a solipsistic outlook upon reality.
Further, to be possible is to be infinite; to be inevitable, finite. The inevitable, by definition, is inevitable: it is a singularity. The possible, meanwhile, can occur, or not. To posit a possibility is to simultaneously posit its opposite. Thus, by positing both the positive and the negative, the original possibility knows no definite existence. It cannot be turned into a finite quality. It is therefore best described as an infinite, which itself is only a concept and not a reality.
Since an inevitable is finite, it holds metaphysical value. Metaphysical value is the necessity for something to exist. It is most often associated with morality. Often the argument is made that that "good" ought to or must be brought into existence, without any other real metaphysical qualification. Still, metaphysicality is the imperative of existence. It, therefore, can only be found in that which exists definitely: the finite. For it is impossible to place an imperative of existence upon that which knows no existence: the infinite. Moreover, since man is unable to distinguish between the possible and the inevitable, all is inevitable. Since life is inevitable, it must be metaphysically commanded. If life is metaphysically commanded, it must be. If life must be, then all life must be: all experiences must be, I also must be. Therefore we find external justification not only of our reality, but also upon our very own personal experiences: and hence our solipsistic nature. The external justification of ourselves is our conception of "God". Our imperative to exist is only valid if given from some "higher-legitimate" source. If I did not exist, nor would my God. God is man's source of "fate", "destiny", or "divine plan".
Supernatural existence, however, is only possible if existence is finite, or an inevitability. Thus, also, the existence of God is an inevitability. However, this only occurs if life is solipsistic. If life is not solipsistic, the imperative to exist is a ridiculous conception, and therefore the imperative for God to exist. To prove that life is not solipsistic, one must break out of the possible-inevitable cycle.
This is not easily done. One might try to simply say that to posit the possibility of God's existence is to simultaneously posit the possibility that he does not exist. However one would again be caught in the cycle of saying that the possible is possible. In other words, to push back the tautology one step is to simply say our possibility itself must exist.
In order to break from the cycle one must leave all possibility behind. If one dies at every moment, and is born again into something new, then there is no possibility, only experience. For possibility is relative, if one abolishes the relative, one abolishes possibility; thus inevitability.
This is done through the "problem of induction", as made famous by both David Hume and Karl Popper. It inevitability makes it impossible to know the possible. Relation could only be found in the result, yet one can never speak to what gave rise to that a priori consciousness. If one places the "problem of induction" upon being, being has no possibility, only existence. Thus it is impossible for us to know existence, and hence it is impossible for us to be solipsistic, and impossible, at least in our own conception, for the existence of a deity. A God may still exist, but anyone who says they know one must exist makes for themselves a pre-determined trap found in the possibility-inevitability cycle. If God exists, no man can know him. Therefore the only religion remaining is the questioning of the existence man cannot know, namely his non-solipsistic external self: otherwise known as nature. This was a common theme in the "Enlightenment".
Still man does have the ability to determine that "Since A=B, and B=C, A=C". Therefore he can still compare realities. Yet man cannot explain how "A=B, B=C, therefore A=C", for to do so would be to place an external-imperative upon existence, which we have previously shown to be impossible.
Yet man's ability to compare nature, without imperative, allows him to inhibit part of the physical realm, while at the same time inhibiting part of the metaphysical realm. Since "A=B, B=C, therefore A=C", he is able to determine the existence of A,B, and C, yet unable to determine how they relate to one another. Thus man is the mitigated combination of both the physical and the metaphysical, the possible and the inevitable, the finite and the infinite. Man exists, not by choice or design, but through pure existence itself. Until man is no longer afraid of this unprovable yet always present and unqualified existence he will always cling to his personal and again unprovable God. Freud was right, the fear of death is the source of our belief in God. He just did not realize death, and life, came at every moment. Until man no longer thinks it important to always exist as he has existed before, he will always have his own God. If man is willing to try something new, he will try new beliefs as well, and hence doubt his central belief in the certain and unquestionable existence of a deity. As Kant said the motto of the Enlightenment is, "Dare to know! Have the courage to use your own understanding."