BhagatSingh ji
So far no one has taken you up on your question. Surely, you knew when you posted this question that you were asking a very sophisticated question. Forgive me for reacting to your obvious intelligence and wit.
Your question:
Why one and only one God? To approach the question one has to stipulate for the sake of argument that there is
at least one God, or Omnipotent Creator. Then one has to sort out whether you are asking for scientific proof or logical argument.
So first I am going to assume that you are willing to stipulate at least one God (or you would not have asked the question the way you did.)
I am not sure if you are asking for scientific proof of God, but if you are, you would most likely be adopting an agnostic position, rather than that of a non-believer. For example, the philosopher Herbert Spencer described the agnostic position.
... admitting the rational necessity of postulating the Absolute or Unconditioned behind the relative and conditioned objects of our knowledge declares that Absolute to be altogether unknowable, to be in fact the Unknowable, about which without being guilty of contradiction we can predicate nothing at all, except perhaps that It exists... CATHOLIC ENCYCLOPEDIA: Existence of God
In other words for agnostics, it is perfectly logical to accept the idea of an Absolute and Self-created Creator (much like Kartar Purakh Akaal murat(t)h Ajoonee SaibhaN, as we Sikhs believe), based on ordinary reasoning. However that Absolute being can never be known completely because of the limitations of our own intelligence. We can only "predicate" that the Absolute being exists.
Next, why only one God, and not two or three or four or more? There are several arguments resorted to by theologians and philosophers of religion.
1. Simplicity of God - God has essential characteristics (for example, God is all-powerful, creative, supportive, destructive, compassionate). If there were several deities, each with one one or more of the qualities that I listed previously, they would have some of the characteristics of the Absolute. But if that were true, then no single deity would be Absolute. From the perspective of Sikhism, two or more deities would be illogical as the Absolute in nirgun form would have no reason to manifest in a vareity of attributes or qualities.
2. God is Perfect - Imagine two or more deities, and all of them were perfect. Then, each would be exactly like the other, they would all be identical, and indisguishable from One who is perfect. Why then would more than One be necessary?
If there were several gods, there would be several perfect beings but “if none of these perfect beings lacks some perfection,” and if none of them has “any admixture of imperfection … ., nothing will be given in which to distinguish the perfect beings from one another” (Aquinas: 158).
3. God's authority is complete and He is the cause of everything. If there were two or more creators acting in the same sphere or in different spheres at the same time, two results are possible and neither of them is logically consistent with the idea of absolute, self-existent and unconditional authority. One: two or more creators could at times work at cross-purposes or contradict one another, demonstrating that none of them were absolute in their authority. Two: If two or more creators work in perfect harmony, then why would more than One be necessary? There can be only One whose authority is complete and is the cause of everything.
4. God is Omnipotent -- all powerful. If there are two deities, and both are all-powerful, and one decided on a course of action, the second deity would be required to help the first. This means that one would be dependent on the other and therefore is not all-powerful. In addition, if the second deity refused to help the first, there would be a conflict. How could conflict be possible if both are omnipotent? Conflict is impossible. There can be only One who is all-powerful.
5. God is Perfect and therefore deserves our complete devotion. If there are two or more perfect gods then both would deserve our complete devotion. Is it logically possible to give our "complete" devotion to more than one god?
Best I can do. I am not a religious scholar. Maybe there is one at SPN who can help out.
But I think Guru Nanak already summed this up.
ੴ ਸਤਿ ਨਾਮੁ ਕਰਤਾ ਪੁਰਖੁ ਨਿਰਭਉ ਨਿਰਵੈਰੁ ਅਕਾਲ ਮੂਰਤਿ ਅਜੂਨੀ ਸੈਭੰ ਗੁਰ ਪ੍ਰਸਾਦਿ ॥
ikoankaar sathnaam karathaa purakh nirabho niravair akaal moorath ajoonee saibhan gurprasaadh||
One Universal Creator God. The Name Is Truth. Creative Being Personified. No Fear. No Hatred. Image Of The Undying, Beyond Birth, Self-Existent. By Guru's Grace~
