Samuel Moyn considers the value and the limits of invoking God in this discussion.
I think that it’s true that we need some basis for saying that people have human rights at all. Now maybe it doesn’t need to be a strong basis. Jacques Maritain argued in 1948 that no one could agree why people had human rights, and so the solution at that time was to say we agree that they have them so long as no one asks why. Maybe it’s enough to say that they have the rights if no agreement is available about why.
Further, we might argue that there is a non-theistic reason that people have rights. Most theistic points of view, even if they’ve said that all people are valuable – say, created, as Genesis 1:26 and 7 tells us, in the image of God – have been engaged for a long time in the business of subjugating, even terrorising, lots of the people who are alleged to have high standing. It seems as if it’s actually in modern times when people either haven’t needed to talk about why people are of high standing, or have given secular arguments for their high standing, that people have been treated more universalistically. Women under less patriarchy, the racially stigmatised with more sense of inclusion.
So I don’t think it’s going to work to say that there’s some necessity to claiming a theistic basis. It could be that it helps to convince certain people that they should treat their fellow men and women equally. And no doubt for those people, for example in the US civil rights movement, it will be a very powerful claim to say that God’s order and God’s decision to make man valuable is what should change their views.