Are we given rights by God, or by government?
Our rights and freedoms are protected by the U.S. Constitution; they are not bestowed by the U.S. Constitution. We have them because we were born human, period. Rights pre-exist law, or else law could not be argued to "protect rights" or to "infringe upon rights."
Our rights are not bestowed by any god recognized by any religion, either. The deist who wrote the Declaration of Independence was not referring to any religious authority, Christian or other, when he invoked "Nature and Nature's God." Humans are very fond of invoking the authority of "God" to enforce their personal opinion. The only way that we can all be equal under the law is to have laws based on NO special authority, religious or nonreligious. The only way we can all have equal rights, and equal moral obligations to each other, is to regard those rights and obligations as independent of any special authority or religious belief. And they are.
Morality precedes religion. Toddlers say "No FAIR!" long before they have any concept about gods. Nobody ever said, "That god commands everything I think is wrong and forbids everything I think is right; yeah, I'll follow THAT god!" We have equal moral obligations to each other because we are all human. Very few of us want to be killed, raped, or robbed and we know that to protect ourselves from such violations we have to commit to protecting others equally. We thrive in groups because we can take care of each other, and we know that if we want to be taken care of in times of illness, weakness, disability or old age, we have to take some responsibility for others in or community, too. We want to be free, and most of us recognize that if we want freedom, we have to give others their own freedom.
An ethic, a social norm, of "treat others as you want to be treated," is based on common human reality and not dependent on any special religious authority. It is secular, and a solid foundation for secular government under which all people have equal freedom for our own belief and practice.