While our society has mostly embraced materialist realism, it remains a practically unlivable personal creed. Humans are material and spiritual beings. Or, as the aliens incredulously put it in a comedic short story by Terry Bisson, "they're made of meat!"
And since with our senses we are able to eat, smell, taste, touch, and see meat, it holds that temptation of believing that we are "only" meat. Well, I don't know very much about the universe, but I do know what it's like to be me. Being human is really the only thing in the universe I have "inside knowledge" of, to paraphrase CS Lewis. And so, this will please the vegans, there seems to be a lot more to meat than is visible from the outside.
Occasionally I come across someone who rejects the "spiritual" reality of the universe. If we're talking cacao ceremonies, then I think we are generally on the same page. But when I say spiritual I mostly mean that there is a "non-material" aspect to being human and that this aspect is at least as real as the material.
Take "truth": you know what truth is, but surely this is even conceptually a "spiritual" reality. Well, says my imaginary interlocutor, I believe in the truth that is demonstrated by science, which is an empirical truth and hence grounded in material reality. Well, true enough (ha), but please use that same line of argument to derive "logic", surely the foundational truth of the entire scientific exercise. This type of discussion, as my wife will testify, generally ends the dinner party.
Logic, I hope you will find, is very hard to derive. And the consequence of logic, the intelligibility of the universe, is what amounts to one of the strongest argument for a universal spiritual ground of being.
This is the "truth-seeking" of the inner, or "spiritual", path which I posit as the second of the two great adventures. If the first is to build a world-changing organization which results in a changed material reality, the end point of the spiritual path depends on the wisdom traditions. To some extent it is a working "theory of everything", one which has not been falsified. Without wanting to engage in too much false equivalency, it is varyingly enlightenment, bodhi, satori, moksha, illumination, kenosis, sanctification, and theosis.
I can't discuss many of these, because I haven't learned much about these traditions. As Dr Kreeft quips: the power of comparative religion studies is to make you comparatively religious!
There will be other guides that can help you with Buddhism, Hinduism, Judaism, and other paths. However I would say one thing about all of them: as you practice and grow in your spirituality, you will come across a lot of false prophets. In general, anyone who wants you to suspend your reason is not your friend. Anyone who tries to profit off you financially is at least suspect. Anyone who limits your freedom and tries to coerce you into choices is evil. And anything that doesn't have a long tradition is likely superficial. Beware, in particular, all the New Age drivel.
My personal journey began when I read Integral Spirituality by Ken Wilber. I made it to the point where he recommended going deep into one tradition. I have done so, to the best of my abilities, and continue to do so every day in the spiritual tradition that picked me historically, geographically, and I believe providentially.
What I did not do: I did not go to the religion supermarket and pick out the flavor of practice that seemed most appealing (this usually leads to some lukewarm poor Westernized copy of Buddhism). And so I think you should start where you are, with the questions you have, with the yearning for truth in your heart, in the place you are. But, since I have found what I believe to be the truth, I will not hide from you that I hope most fervently that you will end up in a similar place.
Copenhagen, Feast of The Immaculate Heart of Mary, June 2023