Monotheism or The One God

In order for a MONOtheistic God to exist, require the existence and understanding of an UTTERLY PERFECT God, which no one can deny that if such God exists, the God would make no mistakes at all, and furthermore, make unbelievably uncompromised ideal truth that no one in the history of mankind could deny or even have the SLIGHTEST DOUBT that HE is the ONE God. I feel that Christian God has much to work on.

First, I myself don't know if such One God exists.
Second, I myself cannot guarantee that it is ONE God, instead of TWO or THREE or even FOUR or even if it doesn't exist at all.
One God is a great dream, that no one else can be better because there is only one at the top, but, how about if the truth is different? We even have pairs for each of us.
I am not saying that there are 2 Gods. Because I don't know that.
But One God? I still have a lot of doubt.
And to admit your doubt is the way to truth and knowledge, however, many would prefer to go straight to the conclusion and say that there is one God, even with the doubt in hand.
However, I've seen so many insensitive souls, that even the most obvious things in front of their noses cannot be seen by them, and yet they are as confident as ever.