Christ is being sung about, specifically. He is being most particularly named and worshipped: ‘Thou art worthy to take the book and to open the seals thereof.’ Look at these doctrines, explicitly set out, which are not set out in this way in any of the psalms. It is in the past tense. They sing, ‘Thou wast slain.’ Where do you find that in a psalm? And yet we are to sing, ‘Thou wast slain’ – words to that effect – ‘and hast [past tense] redeemed us.’ We are to sing in the past tense, looking back on it. ‘And hast redeemed us to God by thy blood out of every kindred, tongue, people and nation.’ It is about the salvation of the Gentiles: we are to sing about the salvation of all nations – people from all nations – by the blood of Christ shed on Calvary. ‘And has made us unto our God kings and priests’ – we are to sing about the priesthood of all believers, this wonderful condition of being a believer: kings and priests. ‘And we shall reign on the earth’, now and in the glorified earth in the future. These are things we are to sing about.
No wonder the apostle Paul in both Ephesians and Colossians urges us to sing in our hearts. We are a Christian church. He specifically says, we are to ‘[Give] thanks always for all things unto God and the Father in the name of our Lord Jesus Christ (Ephesians 5:20). Therefore although so many of them are very godly people, we don’t agree with the exclusive psalm singers on this point. We must sing about Christ and the doctrines of Christ and redemption; we are to sing looking back on what Christ has accomplished, as it is described in the New Testament. That is what Isaac Watts said in his famous preface to his hymnbook, ‘Psalms and Hymns and Spiritual Songs, for the children of the little flock marching to Zion’. What a title! Titles used to occupy the whole page in the old days. He introduces his hymnbook by saying precisely this: we must sing in the light of the great burst of revelation, which is New Testament gospel light.