"the meaning to life".
There is a God, who created everything in existence out of nothing. That includes the earth and all of humanity.
He created man in His likeness and image. In the natural order that He created we have an inherent dignity as children of God. That natural order necessarily includes the rights that come with that dignity. Those rights are not written in stone or in a book somewhere, they are written in our hearts. It is something that we are able to reason to, as human reason is also a part of the created natural order, another gift to us from God.
A little more along those lines:
http://www.tigerboard.com/boards/view.php?message=19117504