A short answer for a complex question:
Judaism in Old Testament times was created to differentiate the 12 tribes from others in the region they inhabited. The Old Testament was the compilation of the oral tradition and history of those tribes.
The Sabbath was a natural break in time, 1/4 of the moon's cycle. Everything then was based on the moon's cycles, because it was the most reliable time-keeper other than the day.
Having a day of rest and worship was important in keeping the commonality of these 12 tribes together. A history that linked them was another. 10 basic laws were another.
It's the history of the birth of a religion. It's fascinating.
Do I believe in the Bible? As a historical document of the beginning and evolution of a regional religion...sure. As the stories that held a people together...Sure.
I can say the same about Hindu scripture or even the Quran. I can say the same about the scriptures of every religion that has scriptures. They're very functional in creating and maintaining a culture.
Most do manage to get people in a more or less ordered fashion from physical birth to physical death (except where it goes beyond a certain degree of warpage, like the Quran and the suicide bombing yoots). Various flavors of atheisms do too. My soul however just could not fit in any of these shoes.
At least you are consistent in your atheism. What I don't get are those who try to reconcile two obviously contrary things. You disbelieve all the miracles of the Bible. So you're consistent.