Christians endure judgment by the world, through it they have the opportunity to praise God and witness of his glory. At the end of time God will judge all mankind and decide who is righteous.
Jesus challenges us to be strong spiritually, remember what an awesome God he is, and do what he tells you through the Holy Spirit to do.
King Jesus teaches us how mankind can confront the Devil and evil effectively: focus on the Holy Spirit through prayer and fasting, and rely on the Word of God.
God wants us to become rich in the Lord, instead of rich in the world. Money doesn't buy joy or salvation; only Jesus Christ can deliver both.
The mustard seed teaches us growth and strength in the Kingdom of God, growing our faith, and resting in Jesus.