'Spirits' in the Bible

and unto the messengers, indeed, He saith, 'Who is making His messengers spirits, and His ministers a flame of fire;'

are they not all spirits of service -- for ministration being sent forth because of those about to inherit salvation?

Then, indeed, fathers of our flesh we have had, chastising us, and we were reverencing them; shall we not much rather be subject to the Father of the spirits, and live?

to the company and assembly of the first-born in heaven enrolled, and to God the judge of all, and to spirits of righteous men made perfect,