There's a big gap between "morality is innate" and "morality can be achieved only through religion."
Religion was created by man, not by god. Religious ideas, including religious morality, are the results, not the causes, of the prevailing cultural attitudes of the societies that created them.
In the modern West, such as the US, "religious morality" is mostly synonymous with the morality of the ancient societies in which those religions originated, which is why religion is so out of step with modern sensibilities.
In other words, Aquinas saw God as the basis for and to all we experience. From the theistic perspective, my question is if moral subjectivism is true, it seems to be self defeating as the concept of truth is fundamentally underwhelmed.
There are plenty of atheistic and some theistic philosophers who see morality as independent of God. I wouldn't necessarily agree with them, but it's just a thought
It seems there is some component of evolved morality; psychopaths would have been excluded by the tribe.
It's such a good belief, that we are blind to it being a belief and blind to its origins.
It's a belief that is so successful because it is true. It comes from the belief that every person has an intrinsic value. Philosophy isn't about rational atheistic science. Science cannot prove or disprove the idea that every human has value.
The Nazis didn't belief that and used science to back up their abhorrent beliefs. They murdered millions of religious People.
The communists also hated religion and murdered millions more of people who thought different. The irony is that they did so in the name of ending oppression.
History and geography will help you see that ideas about innate rights come from religion. But we don't need religion to keep these ideas going.
Just looking at how the human rights movement started should be illuminating.