People had fear of the unknown-and rightly so in most cases. Explanations were made to account for things (ref Big Bang theory). Liege lords demanded allegiance from their peasant-serfs. Yet God is different from secular loyalty, fealty and such matters. There were tribal gods of course, and when different tribal gods appeared in different tribes that caused issues. Actually it was challenging to separate the concept of god from tribal approaches to god. The idea of eternal life freed people from the hopelessness of bad political leadership and death.
A transcendent god differs quite a bit from the Roman amalgam of gods taken from tribes they conquered. Muhammad’s father was keeper of the Kaaba (spirit house) at Mecca with its pantheon of gods. When Muhammad’s father lost his job and was kicked out Muhammad borrowed Christian and Jewish ideas and scripture to write his own transcending approach to god- Allah. Allah was a tribal god without borders able to lead all of the tribes that joined in. The political approach to religion or legiance attaches even to secular concepts such as evolution that is an endemic belief of the Democrat party in the U.S.A. Like Allah, secular atheist evolution runs toward a god-without-borders approach politically manifesting in the hatred of traditional American values and border security in favor of globalism.
People do learn religious ideas from culture. In the Bible God does say that everyone knows him and that they just forget who he is, or repress that sense (in the book of Jeremiah). Secular evolutionists like to explain away God through various reductionist straw men associations, and that is good enough to satisfy those that aren’t too philosophically inclined.
There were a number of arguments in support of the necessity of God- such as the ontological argument, or rather the logical probability of God, that can also be improved to support the idea that a Supreme Being is the source of all that exists. Logical studies for-themselves support the plausibility of a Supreme Being whom is spirit and different than the content of creation. That is, one may use logic and reason to look into the idea that a Supreme being created the Universe in some way regardless of disputes that may arise concerning a posteriori hermeneutics or cosmological mechanics in support or opposition.
A philosophical approach to consideration of the likelihood of the existence of a Supreme Being differs significantly from purely tribal approaches to belief in a tribal god.
The Japanese Shinto ideas seems reasonable yet unbelievable to westerners. The Tori and Kami- spirit gates and spirits fluttering about like birds don’t seem better than the Romans and Local deities such as Janus-the door god, whose temple opened only when the Romans went to war.
Christians of course believe in the person that was Jesus Christ as the Son (member of the trinity) of God, and God Himself, equal to the Father. I think Jesus was the real thing too. It was lucky that he appeared in history when he did.
Christianity is also a transcendent faith-without-borders yet it also instructs Christians to obey secular laws and authorities (that don’t interfere with Christian faith).
So why do some have more religion than others? For the same reasons I would suppose as people believe in anything including science. Personal thought, reliance on authority, prevailing social customs; maybe it is a matter of grace finally. Some people try to treat all religions as the same, and religious belief too, in order to ‘solve’ them. One might use biology to solve physics or geology equally well.
When James Peebles won the Nobel for physics a couple of days ago that showed how much scientists believe in Big Bang theory. It is part of a secular belief system, yet it could be wrong. That is there are other ideas that could account for the existence of the physical Universe in the same scientific vein such as this Universe could be the froth around a 4 dimensional black hole from a Universe with five dimensions, etc…a white hole as it were.