1 Corinthians 9:16
“For though I preach the gospel, I have nothing to glory of: for necessity is laid upon me; yea, woe is unto me, if I preach not the gospel!”The gospel........ the word gospel is used around one hundred times throughout the scriptures, and most of the time the word simply means, any truth that is being preach at the moment the word is being used, is considered the gospel ~ or, the truth concerning that subject under consideration.
When the phrase, the gospel of Christ/God are used, then it would have reference to the teaching of the good news concerning Jesus Christ concerning his redemption work which he undertook for God's elect. Anyone can do their own word study here: https://www.kingjamesbibleonline.org/search.php?q=woe+unto+me+if+I+preach+not+teh+gospel
Let us consider the gospel that Paul wrote about to the churches of Galatia.
Galatians 2:2
“And I went up by revelation, and communicated unto them that gospel which I preach among the Gentiles, but privately to them which were of reputation, lest by any means I should run, or had run, in vain.”We want to consider the gospel Paul considered the true gospel, and that one he considered another gospel, one that he pronounced a curse upon. I would think all of us would desire only the true gospel that the apostles taught, and would greatly desire to avoid another gospel, lest we all run in vain. We all should have the same spirit Paul had, and refuse to give in to any gospel being preached other than what we find here in the epistle to the churches of Galatia, so that we like Paul, would make sure the truth of the gospel continue as pure as we have power to keep it pure. We can never give up this fight, never.
Galatians 2:5
“To whom we gave place by subjection, no, not for an hour; that the truth of the gospel might continue with you.” Paul even refuse to give in to Peter, one of the pillars of the first church in Jerusalem.Galatians 2:11
“But when Peter was come to Antioch, I withstood him to the face, because he was to be blamed. For before that certain came from James, he did eat with the Gentiles: but when they were come, he withdrew and separated himself, fearing them which were of the circumcision."Not only Peter, but even Barnabas was even carried away, and moved from the pure truth of the gospel, thinking in order to be saved by God, then they had to adhere to certain dietary laws, etc. In other words, they had to include their own works of the flesh, adding to what Christ had totally secured for them by being their surety before the law of God.
Galatians 2:13
“And the other Jews dissembled likewise with him; insomuch that Barnabas also was carried away with their dissimulation.”Which will bring us up to one of the most important scripture in the NT, if not the entire Bible, that reveals to us the truth of the true gospel of Christ.
Galatians 2:16
“Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.”We will come back to this scripture later and consider in depth.