In the Old Testament a slave/servant (doulos) of the Lord is a worshiper of the Lord (YHWH).
In 2 Kings 10 Jehu juxtaposes the slaves/worshipers of the Lord (YHWH) with those who are slaves/worshipers of Baal.
The Greek words in parenthesis are from the LXX.
2 Kings 10:19-23
(19) Now, therefore, summon to me all the prophets of Baal, all his servants (doulous), and all his priests. None must be missing, for I have a great sacrifice for Baal. Whoever is missing will not live.” However, Jehu was acting deceptively in order to destroy the servants (doulous) of Baal.
(20) Jehu commanded, “Consecrate a solemn assembly for Baal.” So they called one.
(21) Then Jehu sent messengers throughout all Israel, and all the servants (douloi) of Baal came; there was not a man left who did not come. They entered the temple of Baal, and it was filled from one end to the other.
(22) Then he said to the custodian of the wardrobe, “Bring out the garments for all the servants (doulois) of Baal.” So he brought out their garments.
(23) Then Jehu and Jehonadab son of Rechab entered the temple of Baal, and Jehu said to the servants (doulois) of Baal, “Look carefully to see that there are no servants (doulōn) of the Lord here among you—only servants (douloi) of Baal.”
It is interesting that in the New Testament Christians are slaves of the Lord Jesus. This demonstrates they worship Him as being YHWH. Notice this used in equality with that of the Father (God).
James 1:1
James, a slave of God and of the Lord Jesus Christ.
Ephesians 6:6-7
(6) Don’t work only while being watched, in order to please men, but as slaves of Christ, do God’s will from your heart.
(7) Serve with a good attitude, as to the Lord and not to men.
1. Thayer's Greek-English Lexicon of the New Testament: of the true worshippers of Christ (who is kyrios pantōn, Acts 10:36) Ephesians 6:6 (doulos, page 158).
2. BDAG (3rd Edition): Ephesians 6:7 through wordplay Jesus Christ, as κύριος, is here viewed as the ultimate recipient of the slave's service (douleuō, page 259).
3. Murray Harris: The very existence of the phrase 'slave of Christ' alongside 'slave of God' in New Testament usage testifies to the early Christian belief in Christ's deity. Knowing the expression 'slave of the Lord' from the Septuagint, several New Testament writers - John, Peter, Paul, James and Jude - quietly substitute 'Christ' for 'the Lord', a substitution that would have been unthinkable for a Jew unless Christ was seen as having parity of status with Yahweh (Slave of Christ: A New Testament Metaphor for Total Devotion to Christ, page 134).
Romans 16:18
for such people do not serve our Lord Christ but their own appetites. They deceive the hearts of the unsuspecting with smooth talk and flattering words.
Philippians 3:18-19
(18) For I have often told you, and now say again with tears, that many live as enemies of the cross of Christ.
(19) Their end is destruction; their god is their stomach; their glory is in their shame. They are focused on earthly things.
Instead of their God being the Lord Christ to whom they are to serve (worship), their god was their stomach to whom they served (worshiped).
1. Robert H. Mounce: Their god, the supreme object of their concern, was the belly. (Wycliffe Bible Commentary, page 1329)
Romans 12:11
Do not lack diligence; be fervent (zeontes) in spirit; serve the Lord (tō kyriō douleuontes).
1 Kings 19:10
He replied, “I have been very zealous (zēlōn ezēlōka) for the LORD God of Hosts (tō kyriō pantokratori), but the Israelites have abandoned Your covenant, torn down Your altars, and killed Your prophets with the sword. I alone am left, and they are looking for me to take my life.”
To be fervent (zeontes) in one's spirit in serving (worshiping) the Lord Jesus in Romans 12:11 corresponds to Elijah being zealous in his worship of the Lord God Almighty (cf. 1 Kings 18:36).
In 2 Kings 10 Jehu juxtaposes the slaves/worshipers of the Lord (YHWH) with those who are slaves/worshipers of Baal.
The Greek words in parenthesis are from the LXX.
2 Kings 10:19-23
(19) Now, therefore, summon to me all the prophets of Baal, all his servants (doulous), and all his priests. None must be missing, for I have a great sacrifice for Baal. Whoever is missing will not live.” However, Jehu was acting deceptively in order to destroy the servants (doulous) of Baal.
(20) Jehu commanded, “Consecrate a solemn assembly for Baal.” So they called one.
(21) Then Jehu sent messengers throughout all Israel, and all the servants (douloi) of Baal came; there was not a man left who did not come. They entered the temple of Baal, and it was filled from one end to the other.
(22) Then he said to the custodian of the wardrobe, “Bring out the garments for all the servants (doulois) of Baal.” So he brought out their garments.
(23) Then Jehu and Jehonadab son of Rechab entered the temple of Baal, and Jehu said to the servants (doulois) of Baal, “Look carefully to see that there are no servants (doulōn) of the Lord here among you—only servants (douloi) of Baal.”
It is interesting that in the New Testament Christians are slaves of the Lord Jesus. This demonstrates they worship Him as being YHWH. Notice this used in equality with that of the Father (God).
James 1:1
James, a slave of God and of the Lord Jesus Christ.
Ephesians 6:6-7
(6) Don’t work only while being watched, in order to please men, but as slaves of Christ, do God’s will from your heart.
(7) Serve with a good attitude, as to the Lord and not to men.
1. Thayer's Greek-English Lexicon of the New Testament: of the true worshippers of Christ (who is kyrios pantōn, Acts 10:36) Ephesians 6:6 (doulos, page 158).
2. BDAG (3rd Edition): Ephesians 6:7 through wordplay Jesus Christ, as κύριος, is here viewed as the ultimate recipient of the slave's service (douleuō, page 259).
3. Murray Harris: The very existence of the phrase 'slave of Christ' alongside 'slave of God' in New Testament usage testifies to the early Christian belief in Christ's deity. Knowing the expression 'slave of the Lord' from the Septuagint, several New Testament writers - John, Peter, Paul, James and Jude - quietly substitute 'Christ' for 'the Lord', a substitution that would have been unthinkable for a Jew unless Christ was seen as having parity of status with Yahweh (Slave of Christ: A New Testament Metaphor for Total Devotion to Christ, page 134).
Romans 16:18
for such people do not serve our Lord Christ but their own appetites. They deceive the hearts of the unsuspecting with smooth talk and flattering words.
Philippians 3:18-19
(18) For I have often told you, and now say again with tears, that many live as enemies of the cross of Christ.
(19) Their end is destruction; their god is their stomach; their glory is in their shame. They are focused on earthly things.
Instead of their God being the Lord Christ to whom they are to serve (worship), their god was their stomach to whom they served (worshiped).
1. Robert H. Mounce: Their god, the supreme object of their concern, was the belly. (Wycliffe Bible Commentary, page 1329)
Romans 12:11
Do not lack diligence; be fervent (zeontes) in spirit; serve the Lord (tō kyriō douleuontes).
1 Kings 19:10
He replied, “I have been very zealous (zēlōn ezēlōka) for the LORD God of Hosts (tō kyriō pantokratori), but the Israelites have abandoned Your covenant, torn down Your altars, and killed Your prophets with the sword. I alone am left, and they are looking for me to take my life.”
To be fervent (zeontes) in one's spirit in serving (worshiping) the Lord Jesus in Romans 12:11 corresponds to Elijah being zealous in his worship of the Lord God Almighty (cf. 1 Kings 18:36).