Let me give you an example of non-theistic ideology and philosphy that is related to critical thinking.
It is Objectivism from Ayn Rand and that is both a particular version of thinking, but also a general one for what truth and logic is and how it relates to how we humans ought to behave.
"All thinking is a process of identification and integration. Man perceives a blob of color; by integrating the evidence of his sight and his touch, he learns to identify it as a solid object; he learns to identify the object as a table; he learns that the table is made of wood; he learns that the wood consists of cells, that the cells consist of molecules, that the molecules consist of atoms. All through this process, the work of his mind consists of answers to a single question:
What is it? His means to establish the truth of his answers is logic, and logic rests on the axiom that existence exists. Logic is the art of
non-contradictory identification. A contradiction cannot exist. An atom is itself, and so is the universe; neither can contradict its own identity; nor can a part contradict the whole. No concept man forms is valid unless he integrates it without contradiction into the total sum of his knowledge. To arrive at a contradiction is to confess an error in one’s thinking; to maintain a contradiction is to abdicate one’s mind and to evict oneself from the realm of reality."
The Ayn Rand Lexicon: This mini-encyclopedia of Objectivism is compiled from Ayn Rand’s statements on some 400 topics in philosophy, economics, psychology and history.
aynrandlexicon.com
Now you don't have to explain how you as you understand that text. Rather it is one example of how one human tried to solve the problem of how we ought to live as humans. But it is not the only one as non-theistic. In effect for the categories of religious and non-religious, there is nothing else to say about a given human that is one of those, other that that human is a human.
So what you will find here is a world bwyound your culture as a human, because we are more diverse than just relgious or not.