You bring up an excellent question about the "doctrine of Christ." In fact, you got me to studying a bit. The phrase is found only two times in the Bible. It might do us good to look at these verses:
- Hebrews 6:1 - Therefore leaving the principles of the doctrine of Christ, let us go on unto perfection; not laying again the foundation of repentance from dead works, and of faith toward God,
- 2 John 1:9 - Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.
In both cases, the context indicates that the phrase refers to the teaching of the Bible concerning the person and work of Christ. In other words, the doctrine of Christ is the Bible teaching (or doctrine) about Jesus Christ. Let me explain each passage.
Hebrews 6:1 obviously signals a change in the direction of the book of Hebrews. Up to now, the book has been dealing with the principles of the doctrine of Christ. Now it is time to go on unto perfection. Also, there is no need to lay down again other basic doctrines like repentance and faith. The question then presents itself--what have the first five chapters of Hebrews been dealing with? If we study these chapters, we will find much teaching about Jesus Christ.
- He is the Father's spokesman for the last days (Hebrews 1:1-2)
- He is the "brightness of his glory, and the express image of his person" (Hebrews 1:3); certainly, He must be God
- He is better than the angels (Hebrews 1:4)
- He is given the throne and sceptre of the kingdom (Hebrews 1:9)
- By the grace of God He tasted death for every man (Hebrews 2:9)
- He took on the seed of Abraham (Hebrews 2:16)
- He was made a high priest to make reconciliation for the sins of the people (Hebrews 2:17)
- He is the Apostle and High Priest of our profession (Hebrews 3:1)
- He is a Son over His own house (Hebrews 3:6)
- He was tempted in all points like us yet without sin (Hebrews 4:15)
- He was glorified by the Father to be made our high priest (Hebrews 5:5)
- He because the author of eternal salvation (Hebrews 5:8-9)
I have only picked out several things in this section of the Bible. However, these chapters certainly deal much with the doctrine of Jesus Christ-- is person and work. The remainder of Hebrews continues to speak of Christ, but more and more it points to the perfection of the believers.
The other scriptural use of the "doctrine of Christ" is in 2 John 1:9 where those who abide not in the doctrine of Christ are not of God. If this refers to loving God and loving your neighbor, then we have a works salvation. But the context shows otherwise. Consider the verse in greater context:
2 John 1:7 For many deceivers are entered into the world, who confess not that Jesus Christ is come in the flesh. This is a deceiver and an antichrist. 8 Look to yourselves, that we lose not those things which we have wrought, but that we receive a full reward. 9 Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.
John is dealing with deceivers who have denied the true physical presence of Christ on earth. Historically, we know that there were people who denied that Jesus Christ was born in the flesh or possessed a real body. They felt this was too demeaning to God. How could God dwell in the human body? In order to solve this problem, they created a doctrine that taught that Jesus Christ made a spiritual appearance, but was not in a real body. They denied the incarnation, the virgin birth, and other cardinal doctrines about Jesus Christ.
John taught that those who denied the physical presence of Jesus Christ on earth did not know God as Saviour. That is, the doctrine of Christ could be so perverted that they no longer believed in the true Jesus. In 2 Corinthians 11:4, Paul warned of those who preached "another Jesus." I believe we see this today in many of the cults and isms. They have altered the person of Jesus Christ to such an extent that they no longer preach God's way of salvation. They have denied the doctrine of Christ.
The two verses that teach about the doctrine of Christ give two great truths about this doctrine. First, it is essential for salvation (2 John 1:9). Second, it is basic to our understanding of other doctrine in scripture. Certainly, we should take the doctrine of Christ as a very serious matter.