A new song for justice before all creation

The new song is victory already shown, first to Israel and then to the ends of the earth

O sing unto the LORD a new song; for he hath done marvellous things: his right hand, and his holy arm, hath gotten him the victory. The LORD hath made known his salvation: his righteousness hath he openly shewed in the sight of the heathen. He hath remembered his mercy and his truth toward the house of Israel: all the ends of the earth have seen the salvation of our God.

Marvelous things and a holy arm are public. The nations see because Israel was remembered, not because Israel was discarded. House of Israel remains the named recipient of mercy and truth. Later Christian reading of salvation must not erase that first horizon or turn the sight of the nations into a warrant to coerce them.

Harps, trumpets, sea, and hills gather because judgment will be equity

Make a joyful noise unto the LORD, all the earth: make a loud noise, and rejoice, and sing praise. Sing with the harp and the voice of a psalm; with trumpets and sound of cornet make a joyful noise before the LORD, the King. Let the sea roar, and the fulness thereof; the world, and they that dwell therein. Let the floods clap their hands: let the hills be joyful together before the LORD; for he cometh to judge the earth: with righteousness shall he judge the world, and the people with equity.

Instruments and clapping floods are liturgy stretched to creation. Equity is the last word. Public salvation in this psalm is not a privilege for one modern state and not a technique for making floods behave.