I want to know,

How did David become so convinced in the goodness of God?  What event or experience convinced him so deeply at his core that while being attacked verbally, physically and hiding in a cave, betrayed by those he loved and served he was convinced that God loved him.  That God would fight for him.  Furthermore, this is old testament when most knew the Justice and Power of God, but few knew of His unending love and kindness, His mercy.  David believed that God would judge others, but save him.  How did he get that conviction?

I want it.

(Psalm 69)