Fair enough but I simply dont see what makes you so sure that god exists. An old book is proof of god's existence?
What about the long period of time before that book was made by us, humans?
What about the long period of time before the concept of god even existed?
Why werent we so sure back then that god exists? Because we didnt have an old book telling us that he does exist?
This Book isn't Proof for people before it, it's Proof for People after it (and ofc who were Present during it's reveal)
Just like the Lifetime of a Single Human, starting as a Baby & keeps growing up & learning more, and the greater their knowledge increase, the greater their awareness of problems & the stronger their feelings of both misery & joy.
Same thing can be said about Life of Humanity in general, we are Evolving Creatures, our Ideas & way of Life keep changing over time
This is why the Guidance keeps changing, this Book wasn't available to us since beginning, other "Signs" were provided depending on our progress, for example you can't blame your Primary Teacher for not teaching you about College Lessons, cuz you weren't ready for them.
Currently we reached a Level where this Book is the Sign we need to be reminded of God, but Nations before us had other Signs & Commandements just like they had other Prophets & Religious Leaders
There is no such thing as period of time before concept of God existed,
Atheists automatically don't believe First Humans believed in God, but as a Believer & Religious Person
I know that First Humans believed in God & knew about him & followed his Commands
What went wrong you might ask? well as Life progressed, Humans Nature also progressed, the goodness in them might have increased, but also their evil side, so as Evil & Bad Deeds arise, Humans start to lose some of that Faith & some of that Knowledge & start to question everything, that's when God sends new Prophet & new Signs (What you call Miracles or Proof)
This cycle repeated many times which resulted in True Faith becoming surrounded by Thousands of False Ones & currently in Age of Science, people are now confused about which Path to take as there are so many & who to believe & is there even a Correct Path ... etc
That's why this Book answers all of that, it's the Final Revelation
Just to give an example,
When Humanity were so few, everything was available for them
But as they increase in Numbers, ressources become limited, they can't for example all eat Apples because there aren't enough
This is what started the Term "Possession" & "Trade"
Such development created a New Bad Deed which is "Stealing", something that couldn't have existed when everything was available for everyone, and because of that, Humans had to create "Security" & thus Guards or Law Men were introduced, and to handle such things, and Leader was needed & it gave rise to Politics & Money ... etc
What i'm trying to say is that Life automatically changes over time & with it comes New Life Styles & New Crimes
Which is exactly what happens with Religion & Guidance
It comes gradually & every time Humans learn more from God, they are also introduced to more Problems & more Bad Ideas
Cuz that's simply the nature of Humans, they take something a create two paths from it cuz they are both Good & Evil
So the question is, can we beat ourselves? And defeat our Evil Side
The Enemy is not God, it's Us