'Demonstration' in the Bible

whom God made publicly available as the mercy seat through faith in his blood, for a demonstration of his righteousness, because of the passing over of previously committed sins,

in the forbearance of God, for the demonstration of his righteousness in the present time, so that he should be just and the one who justifies the [person] by faith in Jesus.

and my speech and my preaching [were] not with the persuasiveness of wisdom, but with a demonstration of the Spirit and power,