Passage
For Thou--Thou lightest my lamp, Jehovah my God enlighteneth my darkness.
For Thou--Thou lightest my lamp, Jehovah my God enlighteneth my darkness.
Psalms 18:26 With the pure Thou showest Thyself pure, And with the perverse showest Thyself a wrestler,
Psalms 18:27 For Thou a poor people savest, And the eyes of the high causest to fall.
Psalms 18:28 For Thou--Thou lightest my lamp, Jehovah my God enlighteneth my darkness.
Psalms 18:29 For by Thee I run--a troop! And by my God I leap a wall.
Psalms 18:30 God! perfect <FI>is<Fi> His way, The saying of Jehovah is tried, A shield <FI>is<Fi> He to all those trusting in Him.
The verse centers on "light", "darkness", "thou--thou", "lightest", "lamp", "jehovah", and "enlighteneth". It is saying that the contrast between light and darkness marks a real divide in how people respond to God's work.
The nearby context moves from verse 27's "For Thou a poor people savest And..." into verse 29's "For by Thee I run--a troop And...", so "light" and "darkness" belong inside that flow. In Psalms context, the local focus is worship, trust, the LORD's kingship, and covenant mercy.
A plain takeaway is to answer the verse's own emphasis on "light" and "darkness" with trust shaped by these words, not by a vague optimism outside the passage.