What is a different gospel?
The Apostle Paul wrote,
I am astonished that you are so quickly deserting the one who called you to live in the grace of Christ and are turning to a different gospel — which is really no gospel at all. Evidently some people are throwing you into confusion and are trying to pervert the gospel of Christ. But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let them be under God’s curse! (Gal 1:6–8)
Those who follow a different gospel cannot get salvation.
What is a different gospel? Everything which was not been taught by Jesus is a different gospel.
Jesus kept the Sabbath of the new covenant (Luke 4:16) and apostles also kept the Sabbath (Acts 17; 18) by following Jesus’ examples.
Therefore, Sunday Service is not found in the Bible. Roman Catholic adopted Sunday — the day of sun god Mithra (Please refer to “Finding the Roots of Sunday Worship”).
Jesus kept the Passover of the new covenant (Matthew 26:17–28; Luke 22:15–20) and apostles also kept the Passover by following the examples of Jesus. The Apostle Paul stressed that the Passover should be kept to the end.
In the same way, after supper he took the cup, saying, “This cup is the new covenant in my blood; do this, whenever you drink it, in remembrance of me.” For whenever you eat this bread and drink this cup, you proclaim the Lord’s death until he comes. (1 Co 11:25–26)
Whenever we keep the Passover of the new covenant, we should proclaim the Lord’s death to the end.
Most churches around the world celebrate Christmas. However, Christmas originated from a pagan festival for celebrating the sun god (Please refer to “The Origin of Christmas”.)
Therefore, Sunday and Christmas are all different gospels. Instead, we should keep the new covenant to get salvation.