Rationality is a good tool for science, but it is a poor and perverse method for religion. Try rational reasoning for questions like "What is the purpose of existence", and the best you get is hypermaterialistic theories such as Communism.
Hyperbole masquerading as discussion. communism is a deeply irrational ideology that does not take into account basic human nature or basic human tendencies. Fascism, the flip-side of Communism but suffers the same follies.
If I try your reasoning, then using religion to answer our existential questions will inevitably lead to Islamo-fascism, Christian Fundamentalism and other extremist ideologies. I think I did put a disclaimer that dogmatic thinking is the real enemy. Communism, which is dogmatic, is flawed due to it not being open minded. Rational thinking, demands the evidence of god's existence. If it can be proven, then god/gods can be believed.
I get more compelling, interesting and meaningful discourses from philosophers and scientists on our existential questions than we do from religious figures.
I don't understand the point of rational reasoning for answering life's questions as perverse when Humans have been doing it for thousands of years. Socrates, Plato and Aristotle did.
Rational reasoning doesn't preclude religion. You still can dissect human morality and thinking by looking at it objectively through the lens of Human history, Human behavioral psychology, neuroscience, astro physics.
Science complementing religion is a viewpoint, just as science usurping religion is a viewpoint.
From a rationalist point of view, everything is upto question, god, atheism, current norms of sexuality. That is how society has evolved. by questioning.
I don't know how you came up with communism for scientific enquiry, when communism has been discredited by a lot of economists who have carried out rational thinking.