Charles Thaxton and Stephen Meyer approach the dilemma of human rights in a secular world with all the sophistication of the preteen Woody Allen character in "Annie Hall" who won't do his homework because he's just learned the universe is expanding: "What's the point?"
The point, as British philosopher John Stuart Mill argued more than a century ago, is that humans have dignity, regardless of any perceived source, because they are uniquely capable of behaving with dignity; and they have rights, inalienable in fact, because they have a reasonable expectation that others will continue doing so.
The excessive organized cruelty of this century, including the Nazi death camps and the Gulag, has given "species chauvinism" a bad name. But surely it does not follow that the rights of man must derive from his resemblance to God. Rather, as Mill's godson Bertrand Russell pointed out, it is our worldwide preoccupation with the ancient utterings of ignorant men that, as much as anything, prevents us from bringing about the best world our free intelligence could create. If and when we learn to stop relying on the unknown and start thinking for ourselves, then a shared recognition of basic human rights--both the Jeffersonian freedom from government we are rightfully so proud of, and the Marxian freedom from poverty the Soviets espouse--will be a natural consequence of enlightened self-interest.