In the beginning of his letter to the Galatian churches, the Apostle Paul was beyond belief that they quickly deserted the gospel that they had received. The gospel they received was the one preach by Paul and the Apostle saying that we can be justified apart from works of the law. False teachers had infiltrated the church saying they must be circumcised as Moses commanded in order to be saved. These false teachers were adding works to the gospel message.
As we was voicing his frustration, he wrote:
I am astonished that you are so quickly deserting him who called you in the grace of Christ and are turning to a different gospel—not that there is another one, but there are some who trouble you and want to distort the gospel of Christ (Galatians 1:6-7).
Notice he said, "a different gospel." So the question we might be asking, is there another gospel? We have four biographies of Jesus that are called gospels. There are works outside the Biblical text that have called gospels, such as the Gospel of Thomas and the Gospel of Peter.
We have to remember what the word gospel means. The word gospel means good news. The gospel is the good news of what God has done through Christ's finished work on our behalf. The gospel is the good news that God has made a way for mankind to be made right with Himself. The gospel tells that we can receive the forgiveness of sins and an eternal with God by faith alone.
What other gospel is there? We have the prosperity gospel that promises health and wealth to those who are faithful. When you are sick or poor, it means you did something that made God angry. Imagine the pressure one has to be under. They would have to be perfect for God to give them health and wealth. This gospel fails to teach about how the fall has corrupted everything in the world. When natural disasters happen, it was not because someone failed to read their Bible that morning. This becomes a gospel of works and karma.
Legalism, which is what the false teachers in Galatia were teaching, says you have to do in order for God to keep you. They put rules on people such as give 10% every week or else. Read the KJV or to hell with you. Stay away from R-rated movies and secular music because they are of the devil. Religious do's and don'ts cause more harm and preach a false gospel. 1 John 5:3 tells us that we love God by keeping His commandment yet "his commandments are not burdensome." The burden comes when legalists put restrictions on those who attend their church.
Is there another gospel? If a gospel you hear says you must do additional things for you to be made right with God, you have a false gospel. IF a gospel you hear says God will give you health and prosperity because you are one of his only if you behave like a good child of God, you have a false gospel.
Any "gospel" that adds to the finish work of Christ is no gospel at all. Paul told the Galatian churches that the gospel they are hearing from the Judizers, who are the false teachers teaching them to obey the law to be saved, is no gospel. The gospel we have in the Bible is what God has done for us through Christ on our behalf and can be received by faith alone and not through works (religious or social).