Calvinism is definitely not the gospel. Jesus is the gospel, not calvinism. The gospel is centered on Jesus Christ, and everything that emanates from Jesus is “gospel truth.” And what is it that emanates from Jesus Christ? Everything! From the creation of the universe to the future of the universe, all is dependent upon Jesus Christ. The truths about reconciliation, redemption, and resurrection all require Jesus Christ.
It is the height of idolatry to say, as some Calvinists do, that “Calvinism is the gospel, and the gospel is Calvinism.” I see tulip has been thrown around this thread quite a bit. I I don't wish to rain on anybody's parade but tulips not the gospel either.