The ninetieth Psalm was written by “Moses the man of God.” There is a mistaken idea that David wrote all the Psalms; he did write many of them, Asaph wrote some, a few were written by others, and the writers of many are unknown.
We know the names of many of the writers from the headings of the Psalms. These headings are a part of Scripture and frequently contain information regarding the circumstances of the writer; for instance, the heading of the third Psalm is, “A Psalm of David, when he fled from Absalom his son.” (These headings should not be confused with a little information men have put in above the Psalms; such as, “The security of God’s protection” which is found above the heading of the third Psalm in some Bibles.) By noticing the headings we often see something of the exercises of the soul of the writer, at the time.
We must bear in mind, however, that the Psalms have been given to us by the Spirit of God and are much more than just the recordings of personal exercises; they breathe the spirit of prophecy. They begin with the rejection of Christ in the second Psalm and go on to the joyous praises to Jehovah on the establishment of the future kingdom on earth.
Some Psalms are the prophetic utterances of Christ; others are the expressions that will come from the persecuted faithful remnant of the Jews in a future day; and sometimes Christ identifies Himself with the remnant in their feelings. While David wrote the twenty-second Psalm he never had any experience that could cause him to utter those words, “My God, my God, why hast Thou forsaken me?” These words were prophetic of the very words used by Christ on the cross.
While we do not find Christian experience in the Psalms (often there is the cry for vengeance which will come from the Jewish remnant, but which would be out of place for a Christian) they do express a beautiful faith and confidence in God that has been the cheer of God’s people in many generations. The government of God on the earth is also a theme in them.