Every good thing in life, faith, family, health, happiness all comes from God. He is not shady. He has not a dark side. Let's turn to Psalm 136 . I will read the first part of the verse and you echo that constant refrain.
Mercy means withheld judgment.
You and I deserve judgment. In our hearts we are desperately wicked. It will endure forever. Because God's Blessings are Perpetual, our Gratitude should never cease. God's goodness, His mercy and His truth are perpetual.