God is Spirit
Whenever God is referred to as a Spirit, the word "spirit" does not imply that God and angels have a common nature of which both God and angels would be equal partakers. The resemblance is one of nomenclature only. God is called a Spirit in order that we would perceive Him as being invisible.
Wilhelmus à Brakel, The Christian's Reasonable Service, ed. Joel R. Beeke, trans. Bartel Elshout, vol. 1 (Grand Rapids, MI: Reformation Heritage Books, 1992), 97.