It's simply really, religion was what was used to govern human behavior prior to most governments. Once governments started making laws, they had to incorporate religion at the time to create the bridge between the two for the people at the time. Now it's mostly laws that govern our behavior - which was the inevitable process.
Laws or religion, doesn't matter much, different means to the same end.
I mostly agree, except that in the western world religion has always co-governered with government, but religion wasn't the government itself. For instance, the European monarchies being sanctified by Rome, yet ruling separate from it. It was about divine rule. Religion justified the government, and this is where the later idea of God given human rights came from, especially around the time of the Magna Carta, and eventually the Bill of Rights in the United States.
What I'm proposing is that, if you look at all of world history in its known entirety, and not just Europe and its offshoots, the history of popular rebellion as well as rise and collapse of civilization all revolve around the living conditions that humans will and will not tolerate; and the conditions that humans will
not tolerate are practically universal, even between nations that were formerly not in contact with one another. This tell us that there is a core morality guiding human civilization, derived from our very nature itself, which in turn informs "rights". We therefore don't need them conferred by religion or an abstract notion of the divine when our inherent humanity itself informs it. Where it comes from or which agent gave it to us doesn't matter,
we have it in us.
I feel that in the case of the United States, they deferred to God in order to supersede the egos of humans so that there would be an ultimate authority deferred to when all else fails. After all, given the times, who was a higher authority than God? If the law were written to interpret rights as God given, just as the Monarchs of old were divinely ordained, then nobody could question it. The problem is that people moved away from being devoutly religious to sort of just doing their duty to religion, to now where people don't even care about it. So there is no longer a supreme authority who "grants" our rights, which we arguably need, otherwise any human can twist the story of rights to become something else, and we're fucked.
My argument is that our human nature itself informs rights, based on the world historical trend of civilizations. We don't need God to do it, and in fact shouldn't use God because it's too subjective at this point. The civilizations that end up failing long-term are the ones who deny human self-sovereignty or the personal pursuit of self-determination. Even some dictatorships in history have been very successful because they erred on the side of freedom.
Bottom line... we all know what it feels like to be treated like shit or have our personal autonomy trampled upon. We also know what it feels like to be treated well. I would argue that there are universalisms to these things that transcend even the need for a Godly-ordained list of rights.