Inadvertently, I stumbled across an interesting question while researching the words "gospel" (or "good news"; in Greek, euaggelion) and "preach the gospel" (or "proclaim good news"; in Greek, euaggelizō). The words do not appear that many times in the New Testament and virtually all the time they are used without any description of the content of the word. There is only one passage I know where the content of the word "gospel" is explained:
Now I would remind you, brethren, of the good news that I proclaimed to you, which you received, in which you stand, by which you are saved, if you hold it fast—unless you believed in vain. For I delivered to you as of first importance what I also had received: that Christ died for our sins in accordance with the scriptures, that he was buried, that he was raised on the third day in accordance with the scriptures, and that he appeared to Cephas, then to the twelve. (1 Corinthians 15:1-5)
This is the content of the gospel Paul preached and is the only explanation of gospel, of which I am aware, in the earliest texts of the early Christian movement. Nevertheless, it should not be read as the meaning of the word gospel in all early texts. It is specifically Paul's gospel (Rom 16:25; Gal 1:11). It was not the only gospel being preached in the earliest period, as Paul makes quite clear (Gal 1:6-9; 2 Cor 11:4-6, 13-14). What should we think about the content of the gospel being preached in the communities represented by the Deutero-Pauline Epistles (Ephesians, Colossians), the Pastoral Letters (1, 2 Timothy, and Titus), and the rest of the New Testament?
Paul's gospel is mythical in content, meaning at the very least it deals with stories about Gods and supernatural persons.* In Paul's description above the only historical event that can be verified is that Jesus died. Another item (that he was buried) could have been verified had one been present at the time. The rest of the statement evokes a kind of "salvation history" (Heilsgeschichte), which some theologians postulate as "an account of God's saving acts in human history"; these acts of God, however, can only be seen through the eyes of faith; they are not verifiable as historical events.
In the rest of the New Testament and certain later texts one finds hints that others are quite likely preaching a gospel different from what Paul preached. For example, Mark 1:14 has Jesus preaching the gospel of God and saying, "The time is fulfilled, and the kingdom of God is at hand; repent and believe in the gospel" (1:15; 1 Clem 14:23). If this latter statement is the content of what Jesus preached, the founder of what later became the Christian movement preached a gospel different from what Paul preached. Luke describes Paul preaching a gospel about the grace of God, something that Paul did not mentioned as part of his gospel (1 Cor 15:1-5). The writer in Colossians preaches a gospel about hope (1:5-6; 1:23), something else that Paul does not mention in 1 Cor 15:1-5. The gospel preached by the author of the Didache contained specific instructions about ethical behavior, prayers, and almsgiving, which Paul does not include in his explanation of the content of the gospel in 1 Cor 5:1-5. One cannot assume that Paul's statement of the content of what was being preached is what all writers of the New Testament would affirm.
What do you consider "good news"? Personally, I like to think of the gospel as the life-changing grace of a benevolent God, who gives freely to all (Matt 5:45). Such a gospel is what brings hope in the face of the absolute certainty of death.
Missouri State University
*Myth as defined in the Oxford English Dictionary is "a purely fictitious narrative usually involving supernatural persons, actions, or events, and embodying some popular ideas concerning natural or historical phenomena. It is properly distinguished from allegory and legend, which imply a nucleus of fact."