The Gospel of the Kingdom

In 1 Corinthians 15 Paul presents the centrality of Christ's resurrection to the gospel. Without it, our faith is futile and we are still in our sin. If the resurrection is at the heart of the gospel, and the gospel is 'the gospel of the kingdom', then the resurrection is at the heart of the kingdom.
In 1 Corinthians 15:24, the end, or goal (telos), of Christ's mission is to "deliver the kingdom to God the Father after destroying every rule and every authority and power." The basis of this mission is the love of God, and the means by which he accomplishes his goal is the cross. Here, God's love for the world is poured out through the giving of his only Son, who he sent, not to condemn the world, but to save those who were already deserving of his wrath. That includes us!
When Christ has finally destroyed every rule and every authority and power, those who belong to him, together with the Son himself, will delight to be in subjection to God, that he might be all in all.
Christ has indeed been raised. And so our faith is not futile, we are no longer in our sins, and the hope we have is for this life and forevermore. This is the gospel of the kingdom... the gospel we have received and now proclaim... the gospel of the love of God.