The more you know Him, the better you know Him, the more confident you become, the more secure your joy is… Joy is related to your knowledge of God: little knowledge, little joy; much knowledge, much joy. The more you know of God's glorious truth, of God's great covenants and promises, of God's plans, of God's faithfulness, of God's power, the more joy you experience in life… Our joy is connected to the goodness of the Lord. And the more you understand His grace and mercy and goodness, the more stable your joy becomes, no matter what circumstances may come.
John MacArthur