You have set our iniquities before you,
our secret sins in the light of your presence. Psalm 90:8
I continue to recommend the Psalms to people looking for a devotional order or text. For generations the Psalms served as the bulk of the daily prayer of the Church both in the prayer offices and in the practical devotional life of a people without access to many texts. Though we think of the Psalms as texts of praise and thanksgiving, even liturgical in shape and form, they are also doctrinal. The Psalms teach us both Law and Gospel.
Consider these words from Luther on one verse of Psalm 90, a well known and beloved text:
This is the climax of the drama which God enacts with us. His intention is that we play our part in full awareness of our sins and of death. Yet it is not an evil thing. . . to have this awareness, to complain about our miseries, and to conclude that there is nothing at work in us but damnation. Indeed, one should complain and sigh this way. One should try to arrange and govern one's life in accordance with such sighing. Then it will happen that one becomes aware of salvation.... LW 13, p. 116
Though we instinctively run from admitting our sin and guilt, God calls us to the painful awareness of those sins and to the consequences of those sin for our lives. The secret sins we do not even speak to ourselves, much less to any one else, must be spoken or their hold over us remain. But once spoken, once confessed, we are set free in Christ. The shame of our sin and its guilt is transcended with the greater power of mercy and grace, with the force of the cross and our Savior's death. Then we discover what salvation is, what was required to procure it for us, and what benefit and blessing has come to us, unworthy and undeserving though we be.
Tragically, we live in an age and time in which sins that should be secret are public and proud. Far from the shame of those sins and the strong arm of guilt, we treat evil as if it were neutral or sometimes good. The lack of wrestling over these sins only means that our conscience is silenced and our hearts closed to this voice of God who tells us what we do not want to hear so that we may behold that which is beyond our expectation and imagination -- the blessed salvation of sinners through our Lord Jesus Christ.
No, you could do far worse than to read one Psalm a day and call it good. Would that we were as familiar with the Psalms as were the children of Israel! If you notice, Matins (and Morning Prayer) as well as Vespers (and Evening Prayer) -- indeed all the prayer offices -- are nothing more than frameworks for the Psalms to be heard, prayed, and upon which we meditate in the name of Christ.