The text is Galatians 1
6 I am amazed that you are so quickly turning away from Him who called you by the grace of Christ, [and are turning] to a different gospel- 7 not that there is another [gospel], but there are some who are troubling you and want to change the gospel of Christ. 8 But even if we or an angel from heaven should preach to you a gospel other than what we have preached to you, a curse be on him!
You can see Paul is laying out a case for a false doctrine, or gospel. The interesting thing here is that Paul even puts heavens angels on the alert against preaching another gospel. He and what he and the disciples had been preaching.
I would like you to look at Hebrews 10:29. How much worse punishment, do you think one will deserve who has trampled on the Son of God, regarded as profane the blood of the covenant by which he was sanctified, and insulted the Spirit of grace?
Again in Matthew 12:31 Because of this, I tell you, people will be forgiven every sin and blasphemy, but the blasphemy against the Spirit will not be forgiven. 32 Whoever speaks a word against the Son of Man, it will be forgiven him. But whoever speaks against the Holy Spirit, it will not be forgiven him, either in this age or in the one to come.
I like the tie all three of these verses together by reminding you that Christ sent the Holy Ghost as our teacher and helper. The true gospel, which Paul is speaking of in Galatians is the gospel of grace. In Hebrews he refers to the Holy Spirit as the Spirit of grace. Andy also makes it very clear that we are not to trample on the blood covenant by which he was sanctified. I believe all three of these verses are tied together, and should be taken very seriously for those who are teaching, other than the gospel of grace in the churches of today.
What I am saying here is I believe very seriously that the other gospel Paul is speaking of is the gospel of works. And I am not saying that a man does not have to believe and actively accept the work of Jesus Christ and his crucifixion and resurrection. These are not works, it is not a work to accept the present when it is handed to you. Now it would be a work if when you open a present you as a set of instructions on how to build your own salvation. But this is not the case in the true gospel which is a gift from our Lord.
Look at the different gospels are being taught in churches today. Some saying that salvation comes from baptism, or other sacraments, and others saying that salvation comes from good Works done in Christ's name. Some churches are even teaching that salvation can only come through their particular denomination or church. I like to think that grace is an undeserved favor, something that no man could possibly earn.
Remember now in the Matthews Christ was speaking to the leaders of the Jewish synagogues. They were the believers and teachers of His time. In Galatians in Hebrews Paul was speaking to the Christian church leaders, and even that only Angels. And as Paul says how worse is the punishment going to be for those of trampled on the blood of Christ?