Euangelion - Good News
When there was a war/battle - people in the city did not know what was happening. Worry and doubt over their safety and future. So runners 'good news' bringers would tell what was happening. The words we know as "Gospel" or "good news" in Greek is the word euangelion.
When they won the battle - there would be a procession - with banners. SOS 2:4 He brought me to the banqueting house, and his banner over me was love.
In the 1st century Roman imperial context, euangelion carried specific connotations. First, it implicated an important victory won by Caesar. The news of these war victories travelled around the empire on the tongues of evangelists who were paid for good news and punished for bad news. Additionally, when one Caesar succeeded another, gave birth to an heir, or did any other thing deemed incredible by the Roman elite, they spread the euangelion.
Mark's Gospel takes the message of euangelion and turns it into a literary genre about a different ruler. Mark 1.1 states, "The beginning (genesis) of the gospel (euangelion) of Jesus Christ, the Son of God." Since Jesus is the one whom the euangelion is about, immediately, Jesus replaced Caesar in the consciousness of the first Christians.
All four canonical gospels tell the story differently, but they all end the same way: Jesus rose from the dead. This part is important. The Romans held a monopoly on capital punishment. Life and death were their's and their's alone. For this reason, the Judean leaders bring Jesus before the Roman Governor Pilate asking him to kill Jesus. He complies. Jesus dies, but a few days later, he rises from the dead.
For the Gospel writers and early believers, Jesus' resurrection meant everything. Why? It meant that the Romans failed to exercise power over him through death. This was the euangelion. Jesus' resurrection was the ultimate protest. For people who heard the euangelion of Caesar's victories, to hear of a victory not over the Roman military but over death dealt by the Romans, the new euangelion would, by its very nature, implicate Caesar's powerlessness.
Those who believed Jesus actually rose from the dead were challenged to live in the full logic of that belief; they were challenged to live as though Caesar no longer had any power!