Thus, the "principles [that] lead to that which is most beneficial to society and the individual" pre-exist (or at least exist independently of) the religious dogma, correct? If this is so, why do we need the religious dogma?
To provide income for the clergy.
Most religions claim a "Higher Authority" in order to set it off from just being the ideas of a mortal person. The key to which "Higher Authority" to trust in lies with an intellectually honest appraisal of the said "HA's" ability to demonstrate that reality.
Christians, including Isaac Newton, believe that by examining the prophetic reliability of the Biblical text, as well as the circumstantial evidence of the death and resurrection of Jesus Christ; we can trust in the Biblical God's veracity. Couple that with personal experiences of supernatural transformation, and you have a group of people coming up with a Constitutional Republic.