I think he mean, for a religion that has low to know belief in god(s), does it have a high sense of Spirituality.
Not Buddhist myself, but from looking at it from the outside and reading only a little bit about Buddhism so far, I would say yes it is Highly Spiritual.
Gautam Buddha rejected the Vedic Religion especially 'animal sacrifices' in the name of religion at that time. He preached non-violence.
From the perspective of Theism, the Buddhist philosophy predicts a void after the stage of Nirvana - the sessation of material existance.
Theism is plural and a dynamic reality, so in that light, Buddhism does not reveal the highest platform of Theism ie, Pure Love of God.