Thomas Jefferson, something of a “bare theist” or “Christian rationalist” wrote the preamble to the Declaration of Independence. But how would it have read had he been a secular humanist instead? As charitably as possible, here’ s my educated guess:
“We hold these truths to be good opinions of men; that all men should be deemed equal; that they should be granted by human conventions certain legal rights; and it seems best that among these are life, liberty and the pursuit of happiness.”
Still has some force, I suppose, but hardly provides a foundation or essential framework for the kind of basic universal permanent non-negotiable human rights that Jefferson and his colleagues were hoping to announce to and defend before the watching world. Yet still people will say a belief or disbelief in a self-revealing God is of no political significance in society whatsoever. If you want transcendent abstract entities (like universally binding irreducible human rights), you’d better have a worldview which makes belief in transcendent abstract entities justifiable.
On the other hand, presuppose the existence of a self-revealing infinite God, let that be the basic theological foundation or framework upon which you base your entire understanding of human rights, and you can easily and rationally get something that reads like this:
“We hold these truths to be self-evident, that all Men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the Pursuit of Happiness….”