'Servants' in the Bible

who also made us adequate as servants of a new covenant, not of the letter but of the Spirit; for the letter kills, but the Spirit gives life.

but in everything commending ourselves as servants of God, in much endurance, in afflictions, in hardships, in distresses,

Therefore it is not surprising if his servants also disguise themselves as servants of righteousness, whose end will be according to their deeds.

Are they servants of Christ?—I speak as if insane—I more so; in far more labors, in far more imprisonments, beaten times without number, often in danger of death.