Spirituality, at its core, is simply this:
Cultivating the inner life.
You don't have to believe in God the Mother, God the Father, or a nongendered Source of All Being.
You don't have to believe in any sort of deity, divinity, or spirit, other than the human spirit.
If you do, work with that. If you don't, work with that.
The important thing is to attend mindfully to your inner life.
Mindfully attending to your inner life is the foundation for living a mindful outer life.