It’s not only the religion that is prone to interpretation. Have you seen people interpreting certain part of the constitution differently? For example, even we had difference of opinion on freedom of speech in constitution of USA. It’s the matter of rather proper authority to define clearly convey the meanings. A court in case of constitution.
We will be going off topic if we started to discuss the historical perspective of separation of religion and state in a capitalist society where out of many factors, one would be that economics is based on the concept of interest money, which otherwise is categorically prohibited in the religious text of both Christianity and Judaism.. Very easy to grasp the motives behind the concept.