Fear and faith struggle together in this psalm [Psalm 55]. But faith seems dominant, and the psalm’s message is one of confidence in God. The crucial points for the message of the psalm are in vv 4–5 and 11–12: “By God’s help I will be able.” Trust in God, when activated and confirmed by a word from God, is more powerful than the evil actions of human beings.

MARVIN TATE, PSALMS 51-100, VOLUME 20 (WORD BIBLICAL COMMENTARY), 71.