One God. Period.
In Orthodox Christianity, God is a trinity, so he isn't exactly one.
BUT in a few religions, God is absolute One. How is that possible? What are the characteristics of only One God? Why only One God?
First -we are using man-made languages to describe something not made by man -so it can get a bit confusing trying to describe things.
Also... in biblical scripture, those capable of creating the universe are discussing things with people who have not even begun to study physics -or any science -in any depth.
In biblical scripture, the Word who became Christ is described as BOTH being WITH God and BEING God.
He was WITH GOD IN ONE RESPECT -AND WAS ALSO GOD IN ANOTHER RESPECT.
The fact that the Word also WAS God actually does not negate the fact that the Father is the ultimate authority -and is the God of the Word.
The Word obeys the Father. The Word is ALSO God in that God (the Father) and the Word are inseparable and unified in purpose.
Both of these are quotes from the Word who became Christ.... (bold mine)
Jon 10:28And I give unto them eternal life; and they shall never perish, neither shall any
man pluck them out of my hand.
29My Father, which gave
them me,
is greater than all; and no
man is able to pluck
them out of my Father's hand.
30I and my Father are one.
Mark 10:18And Jesus said unto him,
Why callest thou me good? there is none good but one,
that is, God.
It gets confusing because "one" does not always have the same intended meaning.
It can mean the number one -or it can mean being unified in some way.
To add to the possible considerations, the Word who became Christ is called "the firstborn of many brethren" -and of humans it is written "I said "ye are gods""
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(The following are some things I have been thinking about -based on biblical scripture and coupled with a basic scientific understanding of "reality".
There is ONE thing that exists -let's call it "everything". It has apparently "always" existed. The best answer science has come up with thus far as to why anything exists is "It just was".
It is also obviously dynamic -changing -developing. Every "thing" within "everything" is essentially a subdivision of that one "everything".
If that is what God (unified) meant by such things as "I AM THAT AM"... "“I am the Alpha and the Omega,
the Beginning and
the End,” says the Lord, “who is and who was and who is to come, the Almighty.”" ....then everything would essentially be composed of "God". God would be that "everything" -having/having developed self-awareness, creativity, etc.
If, then, "everything" decided to self-replicate, that first self replication would be both with God -and would be God.
Some would see a developing God as not eternal, but that is not actually true. We, ourselves, refer to ourselves as ourselves even when describing a time before we were aware of anything.
[for example... when "I" was just a zygote.]
As "everything" "just was", it was eternal -but not always in the same state.
We, ourselves, would also be composed of "God" -but would be separated logically and given independent decision-making power, etc.
So... perhaps the following is
literally true....
John 14:20
On that day you will know that I am in My Father, and you are in Me, and I am in you.