Having to do with the deepest part of one's self, which we are creating as we go.
PLEASE, let's cut through the woo-woo.
"The Deepest Part of One's Self" exists in all people, aware or not. It need not be the same depth of place for everyone, less still awareness of that place nor self awareness. "introspection" covers most of that. One's dedication to self-awareness and deeper thinking does not make one spiritual, it makes one self aware and a deep thinker.
Down to brass tacks.
Spiritually requires belief in a spirit. Spirit is something that is at LEAST, an incorporeal part of our self, which can exist independent of the physical.
This is what is meant to some degree by the idea of a soul, by the haunting of ghosts, by the influence or listening of ancestors, by the presence of God or his son on Earth, and many other things going back probably to pre-history and different species of human altogether, I suspect.
I do not believe in it; I am a skeptic. I hope I am nevertheless self aware and somewhat a deepish thinker. I also suspect we have an instinct to believe in such things, that makes us more cohesive and able to deal with our vast ability to recognize patterns in The World, as co-dependent people even across small tribal boundaries. (Just my hypothesis, no proof)
In FACT, what matters is one's attitude and actions toward other people or perhaps other living creatures, regardless of any of the above EVEN AS CODIFIED IN THE CENTRAL TENETS OF MOST RELIGIONS AND FAITHS.
Spirituality is not actually required, and if anyone is going to assert it as something which should have any kind of influence on others (ESPECIALLY when it gives someone else influence) it will need to be measured, defined properly, demonstrated, tested, investigated, and so-on. It has evaded any such attempts thus far, and anyone here who thinks THEY are going to change that, had better be the actual messiah, for whom I and many others have a lot of questions.
Right now, everyone reading this is mid-debate as to what it can be objectively said to MEAN, less still what it might actually be, and a great many people who claim to be or are portrayed as being spiritual, fail to help others to an equal extent. Some do. And others who do not make any such claim, may achieve a great deal.
Meanwhile, whichever opinion is right, it is still the LATTER concern that actually MATTERS. Does anyone think that an all-loving, personal God would disagree? Does anyone want to really justify the opinion that such a deity who is already all-poweful would also wish to be WORSHIPPED? Is he/she/it so egomaniacal and self-absorbed as to put the worst humans to shame? REALLY?
So ditch the BS and start doing stuff, knowing you're just fine and dandy re heaven if it exists. Or try caring less about that and more for the effect of your life upon where and among whom you live. Obvious, really....
For the record, Pascal's wager is hereby reversed. What if adherence to a manmade, self-interested, misinformed faith via such a limited, human lense as the idea that God wants your pathetic praise or attention, prevents one from doing God's actual will which aught to be your unguided, pre-existing humanistic instinct (within a society) anyway, without such grand political aspirations nor petty concerns?