As regards religion that "strict adherence to a set of rules" is the Bible (or in the case of Islam the Quoran) That in itself means that no group (meaning no church or denomination) can interfere with the individuals interpretation of said rules. I grew up in those churches. There is constant flux as members disagree and leave to form a new church on their own. There is no overiding organization that decides who can or cannot be ordained or if any individual or congregation is valid or not. They exist at will. Granted there are denominational organizations (there are at least a dozen different ones that call themselves some permutation of Baptist) but they have no authority over the congregations. Congregations can join them or not; they exist only for mutual support. In affect their is no "organized church" involved.
That's the difference between Religion and Science: Scientists disagree and argue about interpretations of observations UNTIL all the evidence points one way, then the vast majority accept the findings.
Religions make up their minds and schism into a multitude of different sects, there being no FACTS for them to agree on.
One would imagine, that if an omnipotent and omnipresent deity existed, she would be able to get everyone to hear the same message.