From Caliber:
So a basic definition of spirituality is the quality of one’s sensitivity to the things of the spirit. And what are these things of the spirit? These are those that cannot be directly perceived by our senses but whose effects can be deduced or inferred by our observations, like love, justice, peace, etc.
So the basic meaning of spirituality is that it is a term which encompasses everything that we cannot see directly with our eyes, directly perceive by the other senses and know by our mere reason. That is spirituality in its basic meaning
On first read, I have some issues with that definition of spirituality. I think first of all that it allows for one to continue to believe things that cannot be perceived.
Perception is different from faith. I don't need Jesus to come down to the heavens to tell me that the tender emotions, esp love, is very good and healthy. I don't need Zeus or Buddha to help me to see that a purpose in life is valuable, healthy, and necessary.
Faith is believing that love and purpose come from Jesus or Buddha, and that they caused these things as their specific religious traditions teach.
Perception is the acknowledgment that love and purpose, while not tangible phyiscally, are realities of the human experience. Perception also teaches us that love and purpose do not need to be linked to religion or a god, that atheists and agnostics also enjoy these things without a religious truth behind it.
To be sensitive is to be educated and aware. If one is unwilling to consider the evidence, it doesn't change the evidence. It only tells on the person unwilling to consider it.