Some polytheists argue by saying that the existence of more than one God is not illogical. Let us point out to them that if there were more than one God, they would dispute with one another, each god trying to fulfill his will against the will of the other gods. This can be seen in the mythology of the polytheistic and pantheistic religions. If a God is defeated or unable to defeat the others, he is surely not the one true God. Also popular among polytheistic religions is the idea of many Gods, each having different responsibilities. Each one would be responsible for a part of mans existence e.g. a Sun-God, a Rain-God, etc. This indicates that one God is incompetent of certain acts and moreover he is also ignorant of the other Gods powers, duties, functions and responsibilities. There cannot be an ignorant and incapable God. If there were more than one God it would surely lead to confusion, disorder, chaos and destruction in the universe. But the universe is in complete harmony. The Glorious Quran says:

If there were, in the heavens
And the earth, other gods
Besides Allah, there would
Have been confusion in both!
But glory to Allah,
The Lord of the Throne:
(High is He) above
What they attribute to Him!
[Al-Quran 21:22]

If there were more than one God, they would have taken away what they created. The Quran says:

No son did Allah beget,
Nor is there any god
Along with Him: (if there were
Many gods), behold, each god
Would have taken away
What he had created,
And some would have
Lorded it over others!
Glory to Allah! (He is free)
From the (sort of) things
They attribute to Him!
[Al-Quran 23:91]

Thus the existence of one True, Unique, Supreme, Almighty God, is the only logical concept of God.