Inward Assurance (Isaiah 32:17)
In the Old Testament, the words confidence and assurance are different forms of the same Hebrew word. Isaiah adds the concept of quietness, “In quietness and trust” (Isa 30:15) we find our strength. Isaiah also tells us that “quietness and confidence” are the effect of righteousness (Isa 32:17). In the New Testament, the Greek words translated “full riches of complete understanding” (Col 2:2) and “convinced” (Ro 8:38) convey the same idea as similar words in the Old Testament.
Assurance is not based on optimism about your own abilities. Rather it is an inward peace based on God’s righteous work in you. Such confidence is not self-confidence, for that would be false security and reliance on something unreliable (Pr 14:16; Jer 9:23–24). Scripture states that those who have confidence in their own strength (Isa 30:12), beauty (Eze 16:15) or righteousness (Eze 33:12) are to be considered fools (Pr 28:26).
True confidence—rooted in the Lord’s capabilities and his relationship with his children—is a quiet strength that brings rich reward (Heb 10:35–36), a lasting security that is fully satisfying.
Taken from The Woman’s Study Bible