The word for Spirit in the New Testament is the same word as that for breath.
The texts never say God is a being without parts - so the philosophical question if spirit means a non-material but real being is read back into the texts through spin-doctors creating later theology like St Thomas and St Augustine.
In Luke 1:17, Jesus claims that John the Baptist came in the spirit of Elijah. Some have overthought this to mean reincarnation. That would be strange when the Bible says Elijah was assumed into Heaven to live forever. So it supposedly means they had the same spiritual attitude, zeal, and prophetic style.
In John 3:6 Jesus says only those born of the Spirit can be saved. Here spirit means a divine person supposedly. The idea is that the Spirit can change your heart and give you a brand-new, eternal spiritual life.
Spirit is the exact same Greek word pneuma in both texts. But with two completely different meanings? I wonder!
I could argue that Luke shows it is a metaphor.