Ministers raise hands over the congregation at the closing benediction, in imitation of Aaronic priests (Leviticus 9:22) and of Jesus (Luke 24:50). Why?
Jesus blessed the disciples just before He parted from them, ascending into a cloud (Luke 24:51; Acts 1:9-10). Benediction is linked with ascension. Jesus spreads His hands, and then flies up to be enthroned in the glory He had with His Father from the beginning.
And this connects with the common biblical image of the wings of Yahweh. Yahweh protects Israel with His wings as they leave Egypt (Deuteronomy 32:11), Ruth finds refuge under the wings of Boaz, which are the wings of Yahweh (Ruth 2:12), and the Psalmist longs to find refuge in the shadow of the Lord’s wings (Psalm 17:8; 36:7; 57:1; 61:4; 63:7; etc.).
The minister places the Name of the Triune God on the church in the benediction (Numbers 6:27), and he declares that they go out from worship under the protective wings of Yahweh, ascending with wings like eagles. It’s natural, then, that the minister should spread out the wings of his arms over the people as they depart, which, because the minister is commissioned by Jesus to speak and act in His name, are the wings of the Lord – the wings of the Father, the wings of the Spirit-dove, and the wings of the Sun of righteousness who rises with healing.