The Lord has made known His salvation; has shown His justice to the nations. We now know that God has done this through the Incarnation, Passion, crucifixion, and resurrection of our Lord Jesus Christ; but this is from Psalm 98:2, before the Incarnation. It is true that this was prophetic; nevertheless, there was a historic event that occurred also. We do not know the exact details, but this was probably the return to Israel after the Babylonian exile. If this is true, then it was not like the exodus out of Egypt. The return after the Babylonian exile was not a mass exodus, but was spread out over years. Nevertheless, there came a time—perhaps when the foundation of the second temple built—that the nation was told, “The Lord has made known His salvation; has shown His justice to the nations.”
The verse just prior to our Psalm passage reads, “Sing a new song to the LORD, for he has done marvelous deeds.” St. Augustine, in his commentary on the Psalms, wrote regarding this verse: “The new man knows this; the old man knows it not. The old man is the old life, and the new man the new life: the old life is derived from Adam; the new life is formed in Christ. But in this Psalm, the whole world is enjoined to sing a new song. More openly elsewhere the words are these: O sing unto the Lord a new song; sing unto the Lord, all the whole earth; that they who cut themselves off from the communion of the whole earth may understand that they cannot sing the new song because it is sung in the whole and not in a part of it. Attend here also, and see that this is said. And when the whole earth is enjoined to sing a new song, it is meant that peace sings a new song.”
At the time the psalm was written, the nation of Israel was told to “sing a new song.” The “old song” refers to Exodus 15. God tells Israel that this temple will surpass Solomon’s temple. The salvation referred to in this psalm was promised beforehand, is referred to as now, and was also promised to be something in the future. Israel could not “sing a new song” if salvation was not a present thing—and a future thing. This also applies to us. We must look at salvation as three-prong: past, present, and future. It is a past thing in that it took place at Baptism; it is a present thing in that we are being saved now, especially by virtue of confession and the Eucharist; and we will be saved in the future. We cannot rejoice if we just “hope” that we will be saved—“hope” being used as wishful thinking. This is not the type of “hope” referred to in Scripture or through Tradition. The “hope” they refer to is a concrete thing, a thing that will occur—if we persevere. It is for this reason that we rejoice: this three-fold reason. If we only look at salvation as a future thing, we cannot truly rejoice.
Pope Benedict, in his book Saved in Hope, says, “According to the Christian faith, “redemption”—salvation—is not simply a given. Redemption is offered to us in the sense that we have been given
hope, trustworthy hope, by virtue of which we can face our present: the present, even if it is arduous, can be lived and accepted if it leads towards a goal, if we can be sure of this goal, and if this goal is great enough to justify the effort of the journey…Only when the future is certain as a positive reality does it become possible to live the present as well…The one who has hope lives differently; the one who hopes has been granted the gift of a new life.”