This is a frequent claim these days put forth by sincerely religious people who think religion is the only port in a storm of relativism. They tend not to notice how recent an idea it is, however.
There is no trace of it in the great religions at their founding, whether in scripture, the fathers or traditional commentators, etc. All of which assume that moral truth is directly visible, and indeed argue theological points on that basis.
In other words, the claim that the only basis of morality is religion is denied by religion itself.
So then where does morality begin?
Is it "enlightened self interest?"
Is geneticaly encoded?
How did we acquire this universal and objective standard of right and wrong?