Luke 9:1-6 (ESV)
And he called the twelve together and gave them power and authority over all demons and to cure diseases,  and he sent them out to proclaim the kingdom of God and to heal.  And he said to them, "Take nothing for your journey, no staff, nor bag, nor bread, nor money; and do not have two tunics.  And whatever house you enter, stay there, and from there depart.  And wherever they do not receive you, when you leave that town shake off the dust from your feet as a testimony against them."  And they departed and went through the villages, preaching the gospel and healing everywhere.
“Preaching the gospel and healing everywhere.” Gospel, good news, that is what it means. I find it amazing how often people use the term, and never actually express it. I find this as annoying as I do articles about evangelism that fail to proclaim the evangel. Evangel and gospel are the same thing, the word means good news. So the question is what good news?
I went through Paul’s letters once looking for the answer to that, what did Paul mean when he mentioned “the gospel” what did he mean by it. In short, he meant Christ Crucified. The cross was central. It was perhaps even more central to Paul than the resurrection that confirmed the gospel. It was on the cross that Jesus paid for our sins, the resurrection lets us know the payment was satisfactory, that the whole plan worked, that on the cross our sins truly were forgiven so that we would be given eternal life.
The gospel in “the gospels” means pretty much the same thing, though it is often termed “the kingdom of God” or the “Kingdom of heaven” is at hand. This was the good news, God had visited his people, the great prophet had come. It was near, it was at hand. In short Jesus was the good news. Of course this means the kingdom of God was far different than the persistent Jewish myths would have you believe. It was these myths that led the people astray to miss there messiah, myths that made the kingdom of God to be an earthly thing, a glorified earthly kingdom. These myths reappear all too often forming cults, some of whom sequester themselves from society making gawdy furniture and now selling it on late night television in the form of fake fire places. These same people will drive their buggy teams to Bob Evans and terrorize your Sunday brunch with an awful BO, in the name of a smug self-righteousness. No, seriously, Shipshewana gives me the shivers, what an awful tourist trap to visit. Yuck. At times they run wild through the German country side laying waste monastaries and taking over towns, and declaring Luther a lackey of the rich. Today the myths visit us again with books and bad acting, threatening everyone will be left behind because some Palestinian threw a rock and hit an Israeli cop in the head. It gets tiring. Everyone misses the kingdom of God for these things, which are anti-gospel.
The gospel comes in Jesus Christ who had one and only one purpose on his mind, the cross. It was there he would die for your sins, so that you would have the kingdom of God, his rule in your heart where he reigns with the forgiveness of sins, that you might have eternal life in him.