What is the Kingdom of God about? Luke seems to think Jesus was breaking it down very simply for us: love God, love people, be with the King Jesus. In chapter 11, Jesus teaches us how to pray for the way of the kingdom, and at the heart of the prayer is a reshaping of our own hearts toward loving God, loving people, and being with the King.
The second main petition of the Lord's Prayer rules out any idea that the Kingdom of God is a purely heavenly reality. "Your kingdom come, your will be done, on earth as it is in heaven." When we pray this Kingdom-prayer we are praying, as Jesus was praying and acting, for the redemption of the world; for the radical defeat of evil; for heaven and earth to be married at last; for God to be all in all. We pray this for the world, and we pray this for the church.
James makes it abundantly clear that, no matter who you are, you're going to face trials of many kinds. Left to ourselves, we are tossed about like a wave on the sea — directionless and without purpose — and our faith quickly wilts like grass under a scorching sun. Why do trials overwhelm us? Because we lack wisdom and we lack faith. That's why we need wisdom that comes from God; wisdom that compels us to see trials from God's perspective. And this wisdom must involve sustaining faith that involves complete abandonment to God and His purpose for our trials. We learn that in order to become a people "perfect and complete" (1:4) we must be wholehearted and single-minded in our devotion to God, not "double-minded" and divided in our loyalty.