3 “And there has been made in peace a place for Him, and His habitation is in Sion”. Again, Sion is as it were the country of the Jews; the true Sion is the Church of Christians. But the interpretation of the Hebrew names is thus handed down to us: Judæa is interpreted confession, Israel, one seeing God. After Judæa is Israel. Will you see God? First do thou confess, and then in yourself there is made a place for God; because “there has been made in peace a place for Him.”
So long as then you confess not your sins, in a manner you are quarrelling with God. For how are you not disputing with Him, who art praising that which displeases Him? He punishes a thief, you praise theft: He punishes a drunken man, you praise drunkenness. You are disputing with God, you have not made for Him a place in your heart: because in peace is His place. And how do you begin to have peace with God? You begin with Him in confession. There is a voice of a Psalm, saying, “Begin ye to the Lord in confession.” What is, “Begin ye to the Lord in confession”?
Begin ye to be joined to the Lord. In what manner? So that the same thing may displease you as displeases Him. There displeases Him your evil life; if it please yourself, you are disunited from Him; if it displease you, through confession to Him you are united....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)