The main message of Jesus was on "the kingdom of God." I love this beautiful statement on God's kingdom written by J.P. Moreland in The Lost Virtue of Happiness.
"THE GOSPEL OF THE KINGDOM OF GOD - these are not empty words; they are shorthand for a revolution. The gospel of the kingdom is an invitation to a different reality, a different way of living. The kingdom is a new way of relating to people. Where ordinary human life is based on competitiveness and defensiveness, domination and subjugation, treachery and violence, the kingdom is based on the self-giving love of God. This kingdom grows from the seed that falls to the ground and dies - it grows to new life from the death of Christ, which is God's love exhibited to us in its most brilliant glory (see John 12:23-24).
The kingdom brings liberation instead of confinement, celebration instead of despair, a crown of beuty instead of the ashes of mourning. It brings solace to the brokenhearted and the good news of hope for the poor (see Isaiah 61:1-3). The kingdom is a life of flourishing (see John 10:10), an experience of the ongoing presence of a tender, protecting Father, along with His Son and Spirit (see John 17). It means a life of love, peace, self-control, and virtue (see Galatians 5:22-23).
In short, the kingdom is a vision worth dying for. It is a life worth fighting for - against the vision of a world of isolated, self-centered, and empty selves, all vying for prominence and grasping for what they feel life owes them." (pp. 37-38)