Religious beliefs not founded upon rational ethical arguments - example

- I believe gay marriage is wrong ... I will never marry a person of the same gender - that's a personal choice.

- I believe gay marriage is wrong ... I will not permit anybody to marry a person of the same gender ... that's a breach of basic human rights.

Things that are founded upon rational ethical arguments ...

- Slavery breaches basic human rights ... nobody is permitted to own people as property

The opposition to slavery is not just an alternative belief, but is a stance that has a rather solid ethical foundation.