In the prayer of Hezekiah we have a model as to what prayer to the true and living God should be.
The Lord preserves and advances his Kingdom in unexpected ways.
The Lord and not Baal is the one who can provide life and salvation.
The life of Joash teaches us that receiving the finest theological training does not immunize you from apostasy.
By the illness and healing sovereignly brought upon Hezekiah, the Lord causes him to completely turn and trust in the Lord.