Bitterness turns to skeptism which turns to cynicism which turns to an emptiness of the soul.
But Belief opens the door to love. As love grows, God reveals himself more. As God reveals himself more, love increases and trust is created. It spirals upward to ever increasing love and trust and the soul is filled.
Soren Keirkegaard’s parable of the king disguised as a beggar. The king could not make people love him by displaying his power. But as love grew, he could display more and more power because the love others had for him was not based on his power, but on the trusting love.