You would be forgiven if you thought those words incompatible and that naturalistic spirituality was an oxymoron.
The English word spirit comes from the Latin spiritus which means “breath.” When a person dies they breathe their last breath.
Later, in Christianity, spirit came to refer to the supernatural immortal part of humankind given by God. But that is not what spirit originally meant. It simply meant the breath.
I contend that the word spirit refers to our consciousness, our ability to be aware. This ceases at death when we breathe our last breath. We lose consciousness.
Spirituality, then, refers to the quality or state of having or cultivating an expanded or deepened consciousness of our union and communion with reality.
See, no God necessary.