What justifies our claim that all humans are entitled to certain rights?  Especially, in a secular culture, what justifies that claim?  Religious folk might say God does, but that isn't a workable answer for a secular, pluralistic culture.  Yet, if the basis is just human convention, then we have a deep problem--rights are merely constructs and could be eliminated if society was overcome by new attitudes of fear and exclusion.  These are the dangers.

This article from Aeon discusses the issue. For example:

But is it enough to rely on the supposed fact that human rights are embedded in a liberal democratic culture? Or do we need to be able to step back from that culture and offer an objective justification for the principles embedded in it, as the philosophers have long supposed? The problem is that social expectations and cultural assumptions not only vary significantly across societies, but that they are fragile: various forces ranging from globalisation to propaganda can cause them to change dramatically or even wither away. Would rights against gender or racial discrimination disappear if sexist or racist attitudes come to predominate?

The author believes that rights must rest on something other than a human construct.  His view is

that human rights are rooted in the universal interests of human beings, each and every one of whom possesses an equal moral status arising from their common humanity. In other words, in defending human rights, we will need to appeal to the inherent value of being a member of the human species and, in addition, the interests shared by all human beings in things like friendship, knowledge, achievement, play, and so on.

Human rights in American thought derived from a mix of New England Congregationalism (with roots in Reformed theology), Enlightenment reason, and Romanticism.  Kant derived them from his view of autonomy.  Neera Badhwar, in the book I recently read, Well-Being, discusses autonomy within a ne0-Aristotlean perspective which could be helpful in deriving a justification for rights.  

Consider this earlier post on the role of William James in the religion of democracy.