The Gentle God
“Your gentleness made me great.” Psalm 18:35 (parallel with 2 Sam 22:36) A mystery here against which I am scratching, trying to understand. The one whose greatness is unsearchable (Psalm 145:3) is also gentle and as He stoops down” (NIV translation) He makes me great.
From the New International Dictionary of Old Testament Theology,
(ii) Psalm 18:27 . David praises God for the victory going to the afflicted, while the proud are afflicted in this typical divine reversal of circumstances. In 18:35 , in the third part of the verse, we have “and your humility has made me great” (NIV you stoop down to make me great; note 2 Sam 22:36, “and your help has made me great”). Many conjectures have been proposed for the unusual form, but the sense of divine humility in 18:35  is not impossible (Ps 113:6). God’s condescension has saved David. God had stooped to conquer David’s enemies. The divine character had been exhibited in seeking and promoting the welfare of David. There seems to be no incompatibility between humility of this character and the exercise of God’s controlled power (Dawes, 46).