Lately Katinka posted (on Squidoo) an interesting page about spiritual questions. Then I said I think such questions derive from the age-old Philosophy questions in the Classical dialogues. Here are a few examples:

What is truth?
What is virtue?
What is beauty? (aesthetics topic)
What is ethical? (ethics topic that Pythagoras, Socrates, Plato focused on)
(the previous 2 are axiology's topic)
What is knowledge? (epistemology's topic)
What is? (metaphysics' topic)
What is being? (metaphysics' topic in ontology)
What is reality? (metaphysics' topic in cosmology)

I think most important questions are either derived from the ones above or the dialogues the ones above lead to: when they lead to more questions.

I would like to find or make a complete list of Socrates' important questions. Katinka suggested I start a post on these here but that these questions are maybe just a different topic than the ones she wrote about. I think the one I came up with for metaphysics should lead to all questions. Maybe the question would usually be the one of ontology or cosmology but I think in Socrates time they had not defined those yet, and Hermetic and Pythagorean esoteric Philosophy does seem to imply one should as 'what is,' because Hermetism or also Pythagoreanism have the answer 'Te Olos' ('The All,') i.e. all-cause Chaos or Parabrahm.

However, I think the Classical list, maybe with a few more modern ones that lead to analysis of language, could be as long as the Delphic Maxims.

Also, Philosophy, the 'love of wisdom' requires all possible intelligence to be used, and that of the Nous extends from the divine to human, so spiritual questions are Philosophical by definition. Maybe some modern spiritual ones cannot be reached from the old questions, but my hypothesis is that they can.