Rights can be unalienable even if they are not endowed by God. Inalienable rights can even be created by a government! For example, before slavery was outlawed, it was at least theoretically possible to sell one’s (supposedly unalienable) liberty away and become a slave. By outlawing slavery, the Federal Government closed that loophole. Arguably, they could open it again, by amending the Constitution. So, the right of liberty is only unalienable given the Constitution as currently written.
In my opinion, grounding unalienable rights in God is a little dangerous because it might open the way for atheist citizens to lose rights or atheist government officials to take them away.
THE absolute rights of man, considered as a free agent, endowed with discernment to know good from evil, and with power of choosing those measures which appear to him to be most desirable, are usually summed up on one general appellation, and denominated the natural liberty of mankind. This natural liberty consists properly in a power of acting as one thinks fit, without any restraint or control, unless by the law of nature : being a right inherent in a us by birth, and one of the gifts of God to man at his creation, when he endued him with the faculty of freewill.
But every man, when he enters into society, gives, up a part of his natural liberty, as the price of so valuable a purchase; and, in consideration of receiving the advantages of mutual commerce, obliges himself to conform to those laws, which the community has tough proper to establish. And this species of legal obedience and conformity is infinitely more desirable, than that wild and savage liberty which is sacrificed to obtain it. For no man, that considers a moment, would wish to retain the absolute and uncontrolled power of doing whatever he pleases; the consequence of which is, that every other man would also have the same power; and then there would be no security to individuals in any of the enjoyments of life. Political therefore, or civil, liberty, which is that of a member of society, is no other than natural liberty so far restrained by human laws (and no farther) as is necessary and expedient for the general advantage of the public
— Blackstone
I think of inalienable rights as intrinsic to man’s nature. They are above government and any government that claims the right to bestow them or take them away is illegitimate.