Why is it impossible to derive morality from religion?

There are two well-defined sides to the argument over deriving morality from religion. Though there are many examples supporting the idea that one can gain morality from faith, this answer will argue solely against this notion.

One way to understand how it is impossible to gain morality from religion is to examine the nature of morality and religion. Morality is a fluid concept throughout history, while religion is resistant to change. For example, Martin Luther...

There are two well-defined sides to the argument over deriving morality from religion. Though there are many examples supporting the idea that one can gain morality from faith, this answer will argue solely against this notion.

One way to understand how it is impossible to gain morality from religion is to examine the nature of morality and religion. Morality is a fluid concept throughout history, while religion is resistant to change. For example, Martin Luther argued against the morality of Catholic indulgences in his Ninety-Five Theses. At the time, Luther was not attempting to break away from Catholicism, but change it. Yet when the Catholic church did not listen to his ideas, Luther used his own morality to start the Protestant Reformation.

Another way to argue against a connection between morality and religion is using historical examples of times when religion was used to justify immoral acts. For example, in the antebellum American South, passages from the Old Testament were commonly cited to defend American slavery. Abolitionists used the ideas of Enlightenment thinkers, many of whose writings influenced the creation of the United States, to argue against slavery. In the end, morality gained from the Enlightenment, and not religion, led to the freedom of American slaves.