For we proclaim not ourselves but Jesus Christ [as] Lord, and ourselves your slaves because of Jesus.As I briefly explained, Israel had a long and essential Servant of Yahweh tradition from which Paul derived a lot of his servant/slave rhetoric. Here are some details...if you read through all of this, you'll get to a discussion of Paul!
Servant of Yahweh, Servant of the Lord in the Old Covenant Scriptures
The Hebrew word for servant, eber, denotes "authorized messenger of the LORD": the presence of Yahweh's servant equated with Yahweh's presence and carried the same clout! In Israelite history, the servant of the LORD was chosen by Yahweh, the LORD Himself; from its inception, the "Servant of Yahweh" concept implied the position of a slave.
For Israel, the highest tribute you could give a person was to call them "the servant of Yahweh." In the Hexateuch Moses is "servant of the LORD [Yahweh], and "Moses My servant." In fact, "Moses the servant of Yahweh" is just about Moses' official title, and later in the New Covenant Scriptures, the author of Hebrews (13:5) describes Moses by saying, "Moses was faithful in all His [Yahweh's] house as a servant." Joshua, "Moses' servant," who led Israel into the Promised Land also was "the servant of the LORD" (Joshua 24:29).
Through Jeremiah (7:25) Yahweh says, "I have sent you all My servants the prophets." Jeremiah even calls Babylonian King Nebuchadnezzar "My [Yahweh’s] servant" (25:9, 27:6)…although he fantasized himself Top Dog, Nebud unknowingly was God's servant and the vehicle for liberating God's people.
Also, compare Jeremiah 30:10
So do not be afraid, my servant Jacob--—it is Yahweh who speaks--Israel, do not be alarmed: look, I will rescue you from distant countries and your descendants from the country where they are captive. Jacob will have quiet again and live at ease, with no one to trouble him.  For I am with you to save you...The psalm-singers call themselves the LORD'S servants, and according to Psalm 34:22. "The LORD redeems the soul of His servants, and none of those who take refuge in Him will be condemned." In Zechariah 3:8b of the Book of the Twelve [sometimes referred to as the "Minor Prophets"], the angelic messenger calls the promised Messiah a servant: "...for behold, I am going to bring in My servant the Branch."
But do not be afraid, my servant Jacob, Israel, do not be alarmed: look, I will rescue you from distant countries and your descendants from the country where they are captive. Jacob will have quiet again and live at ease, with no one to trouble him  Do not be afraid, my servant Jacob--it is Yahweh who speaks--for I am with you…
2nd Isaiah's Servant Songs, "Songs of the Suffering Servant"
In the book known as Isaiah, "servant" first appears in Isaiah 41:8, where it indisputably refers to Israel, "created by Yahweh and not to be forgotten."
Four poems from the unidentified Deutero-Isaiah are known as the Servant Songs or the Songs of the Suffering Servant. Biblical scholarship considers these poems a related whole that explicates a coherent identity of the Servant of Yahweh. Generally speaking, 2nd Isaiah (chapters 40-56) is considered exilic, although the literary style is more consonants with the post-exilic era of the scribes (as in 3rd Isaiah, chapter 56-66), but a prophetic message of hope would be work well during the gloomy discouraging days of exile!
* 42:1-9 | The servant will bring justice to the nations, the peoples
In this first servant poem Yahweh describes the servant as His chosen, bearer of His Spirit, who quietly and gently will bring justice to the peoples of all the earth, to mediate a covenant for all and to liberate the unfree.
* 49:1-9a | Israel as a light to the nations, the peoples
In the second poem the servant, clearly distinct from the people Israel (though in Isaiah 49:3 Yahweh addresses the servant as Israel...that's usually considered a gloss by a later redactor because in himself the Servant subsumes the meaning of the ideal Israel) ...continuing, in the second poem the Servant mentions being called from the beginning, sheltered in Yahweh, and speaks of both discouragement and trust. Yahweh promises the Servant will be a light to the Gentiles and leader of the people's restoration.
* 50:4-11 | My back to those who beat me
Here the Servant tells of being taught a message for the weary and he describes his sufferings that were a result of his obedience and confidence in Yahweh. In 50:10-11 Yahweh first encourages those who listen to the Servant, and then addresses those who scorn and spurn the Servant.
* 52:13-53:12 Bruised for our iniquities
In 52:13-15 Yahweh speaks of the Servant's humiliation, wise actions and later exaltation, though the Servant’s appearance suggests anything but dignity and will astonish nations and kings! Beginning at Isaiah 53:10, the prophet-servant becomes the instrument of Yahweh, Who acknowledges His Servant. Here the Servant becomes a trespass offering but at last he will be exalted and will justify the nations, the *peoples.* Deliverance from exile and deliverance from sin, separation, debt and bondage (essentially the same in the Hebraic economy) are joined in a single person, this Servant of Yahweh. Since mediator Servant was a prophet, too, here priest and prophet meet in one individual and with his assured exaltation, prophet, priest and king meet together in the Suffering Servant.
The Person of the Suffering Servant - speculations
Ages ago I copied this and have no clue as to the source, sorry!
"the exilic prophet gradually passed from the conception of Israel as a nation to [the concept of Israel as] a person through whom its true destiny would be realized. In this passage the Servant's mission in this passage seems highly bound up with the restoration."Here’s a paraphrase from some of my class notes; I'm not sure of my sources here, I've learned to be a lot more careful than when I took these notes:
Some consider the Servant of Yahweh a personification of the ideal Israel, endowed with Yahweh's Word and Spirit; others believe the servant was a metaphor for Judah's suffering exile in Babylonia (Judah, the southern nation, was Deutero-Isaiah's original audience), and that by its misery and distress, Judah vicariously delivered healing to other nations by witnessing to Yahweh's salvific, justifying power. Also, given that Israel's prophets characteristically were called "my servants, the prophets" and "servant of Yahweh," the servant may have been an individual, and if the servant was a real prophetic figure, Jeremiah would be a likely candidate, since according to Kings and his self-titled book Jeremiah was a social outcast and physically very ill-treated. Besides Jeremiah, other suggestions include Judah's king in exile, Jehoiachin, 2nd Isaiah himself, and Zerubbabel, the first post-exilic governor of Judea. However, Deutero-Isaiah may have intended the *Servant* illusion to be indistinct and nonspecific, not so much particularly historical but more of a *standard model* for the people of God everywhere and in every time. The church historically has interpreted the Suffering Servant of 2nd Isaiah to mean the Crucified Jesus…and Jesus calls the church, Jesus calls us to service, only service, in the power of the Holy Spirit!
Servant and Slave in the New Covenant Scriptures
In his epistles, Paul of Tarsus draws upon the *servant* image, applying it to Christ Jesus [Philippians 2:6-8; Romans 15:8], to himself [Philippians 1:1; 1 Corinthians 3:5, 4:1, 9:19; 2 Corinthians 11:23; Romans 1:1, 1:9], to individual Christians [1 Corinthians 4:1, 7:22; Galatians 5:13; Romans 6:16-19 (this is Paul's marvelous slaves of righteousness passage: v. 18 literally reads "your were enslaved to righteousness!"), Romans 14:18], those in political authority [Romans 13:4, from the passage Martin Luther famously interpreted] and to the church at large [1 Corinthians 4:1, Galatians 5:13; Romans 14:18].
Possibly Paul's most celebrated *servant* passage is his quoting in his letter to the Philippian (2:6-8) church what unquestionably was one of the very earliest Christian songs:
although He existed in the form of God, did not regard equality with God a thing to be grasped, but He poured out Himself, taking the form of a slave [morphen doulou, to transliterate, since this blog template doesn't support Greek], and in the likeness of men having been born, and being found in appearance as a man, He humbled Himself by becoming obedient to the point of death, and that death by a cross.According to Mark (10:45) the gospel-writer, in his own words Jesus declares the culmination of His servanthood: "For even the Human One did not come to be served, but to serve, and to give His life a ransom for many." Later on, in an immediate reminder of the 2nd Isaiah's Servant of Yahweh Songs in Isaiah, in Acts 4:27, 4:30 and Acts 3:13, Luke reveals how the emerging church called Jesus "servant."