'Ministers' in the Bible

Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.

But in all things approving ourselves as the ministers of God, in much patience, in afflictions, in necessities, in distresses,

Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works.

Are they ministers of Christ? (I speak as a fool) I am more; in labours more abundant, in stripes above measure, in prisons more frequent, in deaths oft.