In the Scriptures the gospel is said to be "the gospel of God" (Romans 1:1). This means that the foundation of it is built on God, by God, and He alone is the Author of it. God Almighty has the authority in this matter. The phrase gospel of God especially tells us that it is NOT of man, meaning neither by man, from man, or about man. In other words, man did not come up with it, and it is not derived from the of man's wisdom (Galatians 1:11-12). Man is not authorized to do such a thing but rather is forbidden. The gospel is dependent on God from its source of origination and in it's continual sustaining.
This gospel is God-centered in everything about it. This is one reason why God receives and deserves all the glory due His wonderful name for the formation, fulfillment, and success of this gospel. Sinful man tries to steal the glory from God by twisting the gospel to favor the wisdom and glory of man. God did not seek the counsel of man in any matters at all, especially in things that are gospel related where the redemptive glory of His character is revealed. God will never share His glory! He is an extremely jealous God. So, God puts the label of "another gospel", or "false gospel" on any gospel that is humanistic. God is only interested in what He says about Himself, not an idolatrous view of a god man has dreamed up out of his own evil imagination.
Since God is all knowing, all wise, eternal, unchanging, faithful, consistent, and all powerful it is best to only trust Him to know and do what is best in the salvation of sinners. Man is not trustworthy or qualified to formulate a gospel. Man will fail every time. Man will only sink himself deeper and deeper into trouble as he favors and formulates false ways that are not God's ways.
In our gospel defense series it is our goal to progressively define the gospel from God's word itself. As we see the biblical description of each gospel facet we need to carry over these definitions from week to week as they are pieced together as a whole. The gospel is of God. God's people love this truth.