The theist will say that man-made laws are arbitrary and can be erased and re-written at any moment and thus, whatever is right and wrong is only temporary. He will argue further and say that God's laws and morals are timeless and written in stone and are therefore not subject to the changing winds of political parties and leaders.
I disagree. While is do agree first that yes man-made laws can be changed at a moments notice and are therefore only binding when they are enforced and in power. I also believe that God's laws change over time too and that they are not permanent and that evolving morals can be a good thing.
First a person or persons can re-write a religion, I mean literally re-write the doctrine on which the religion is based on. All you have to do is look at the different sects with in the religions. Joseph Smith founded the Mormon church in upstate new york on a vision he had, and re-wrote the christian faith with new rules and regulations. The Shiites and the Sunnis disagree and a great number of things even though they all pray to essentially the same God. In fact, Islam is a complete re-writing of Christianity and Judaism.
Once slavery was excepted as the norm, then it wasn't. The Bible justifies slavery, but intelligent thinking, moral people decided it wasn't justified under any circumstances, and they changed moral attitudes toward slavery. If biblical morals were written in stone, we'd still have slavery and we'd still be stoning people to death for adultery and working on the sabbath.
Do you want to live in a society like that?