What is the Gospel--the Gospel of Christ?

For years the Worldwide Church of God which I was a member of taught a message about the Gospel of the Kingdom of God, thinking this was the Gospel which Jesus told us to preach and that it was this 'Gospel' which when preached brought people into a knowledge of Salvation. I have learned since that we were preaching the "Jewish" gospel which the evangelistic Diaspora Jews had been preaching from the time of the Maccabees to the time of Christ. But the simple Gospel the apostle Peter preached in his first sermon in Acts 2 was about the death, burial and resurrection of Jesus Christ. The result of Peter's sermon preaching this 'Gospel' brought 3,000 souls to repentance and baptism. So what really is the "Gospel of Salvation," called alternately "the Gospel of Christ"? Click on the title of this blog to log onto an article I just posted about what the Gospel of Salvation really is. The Jewish gospel drew many Gentiles into their synagogues, and caused those Gentiles to believe in the One true God of Israel, Yahweh, and many believers have come into the Sabbatarian Churches of God due to the preaching of a similar gospel about the coming Kingdom of God, but it is not the Gospel preached by Paul, John, Peter and the other apostles. All believers ought to be on the same page with this essential information, for it is this very Gospel which Jesus commanded us to be preaching to the entire world before he would come again (Matthew 28:18-20 and Mark 16:15-18). Be sure to click on the title of this blog to link to an article which clearly defines the Gospel of Salvation. A major Sabbatarian Church of God leader has read it and approves of it 100 percent, interestingly. We all need to be on the same page with this one, as Jesus in Matthew 28:18-20; Mark 16:15 and Matthew 24:14 put some pretty serious emphasis on it.