Greg Gilbert (What Is the Gospel? gives a well reasoned summary of the Gospel message.

God
– Creator
– Holy and righteous

Man
– All guilty of treason against God
– All fall under God’s active judgment against sin

Christ
– A fully divine, fully human king
– A suffering king
– A substitute
– A resurrected and ascended king

Response
– Faith relies on Jesus for one’s righteousness
– Repentance acknowledges the rightful king and leads to real change

Kingdom
– God’s redemptive reign
– God’s present reign
– God’s reign to be consummated
– Christians live for the King