It can be looked at from two different angles.
One is the Declaration of Independence organic approach. Some consensual concept of God is in there, We might not all agree exactly on it, but we still agree in not picturing this God as hanging trees upside down by their roots from the clouds. There is a sense to the created order.
The other is the isolated Constitution approach. This has no affirmation of a transcendent source of rights, and so rights become whatever men managed to morph them to be.