Alexa and whitewavemark, I don’t think, in general, religions are established by rulers, though they may be used and abused by rulers and political leaders.
Even religions have a range of normative ethical principles. Take, for example, Christianity. People make moral choices based on some of the following:
Rule-base principles, either taken directly from the Bible or from some system that is theologically based, such as Aquinas’ precepts of Natural Moral Law.
Ends-based principles, for example, doing things in order to achieve religious credit (be seen as good) or to get to heaven and avoid hell.
Virtue-based principles, for example ‘What would Jesus do’?
Utilitarian principles, for example ‘greater love hath no man than this, that a man lay down his life for his friends’.
The same is true when it comes to secular approaches to ethics. It’s extremely rare for anyone, religious or not, to have a single basis for their morality.
To reduce the ethical influence of religion to a single rule or set of rules is to misunderstand both religion and ethics.