In 1719 Isaac Watts published The Psalms of David Imitated in the Language of The New Testament And Applied to The Christian State and Worship. This was a new metrical Psalter for singing in the churches, but he wrote the words, taken from the Psalms (OT), with a view to the Gospel (NT). In his preface he wrote a defense of this approach. His words, which follow below, can also help guide us today as we read the Psalms in a Christ-centered way.
"I come therefore to explain my own design, which is this, To accommodate the book of Psalms to Christian worship. And in order to do this, it is necessary to divest David and Asaph, etc., of every other character but that of a psalmist and a saint, and to make them always speak the common sense, and language of a Christian..."Where the Psalmist uses sharp invectives against his personal enemies, I have endeavored to turn the edge of them against our spiritual adversaries, sin, Satan, and temptation. Where the flights of his faith and love are sublime, I have often sunk the expressions within the reach of an ordinary Christian: where the words imply some peculiar wants or distresses, joys, or blessings, I have used words of greater latitude and comprehension, suited to the general circumstances of men."Where the original runs in the form of prophecy concerning Christ and his salvation, I have given an historical turn to the sense: there is no necessity that we should always sing in the obscure and doubtful style of prediction, when the things foretold are brought into open light by a full accomplishment. Where the writers of the New Testament have cited or alluded to any part the Psalms, I have often indulged the liberty of paraphrase, according to the words of Christ, or his Apostles. And surely this may be esteemed the word of God still, though borrowed from several parts of the Holy Scripture. Where the Psalmist describes religion by the fear of God, I have often joined faith and love to it. Where he speaks of the pardon of sin, through the mercies of God, I have added the merits of a Saviour.
"Where he talks of sacrificing goats or bullocks, I rather choose to mention the sacrifice of Christ, the Lamb of God. When he attends the ark with shouting into Zion, I sing the ascension of my Saviour into heaven, or his presence in his church on earth. Where he promises abundance of wealth, honor, and long life, I have changed some of these typical blessings for grace, glory, and life eternal, which are brought to light by the gospel, and promised in the New Testament. And I am fully satisfied, that more honor is done to our blessed Saviour, by speaking his name, his graces, and actions, in his own language, according to the brighter discoveries he hath now made, than by going back again to the Jewish forms of worship, and the language of types and figures."