Psalm 50 (51): The Sacrifice Acceptable to God is a Broken Spirit
We are called to union with God and the only way to do this is through silence, stillness, and unceasing prayer. Psalm 50 (51) is a beautiful prayer of repentance and hope that can be recited each day: morning, noon, or night.
Psalm 50 (51) was written by the Prophet King David after he acknowledged and confessed his sin before the Prophet Nathan (2 Samuel 12), which involved adultery with Bathsheba and the murdering of her husband Uriah. Thus, it is the prayer of a terribly sinful person...like everyone one of us. And like the Prophet David, when we choose to pray it, we are telling God, 'I know I am not worthy of your love, sacrifice, and mercy, but if I repeatedly give my heart to you, you will make me new again. And I will learn to love you more than anything in this world and grow closer to you everyday.'
This is the same type of reason that priests and deacons recite Psalm 50 (51) it in its entirety at Divine Liturgy (first, prior to the start of Divine Liturgy the Deacon says it quietly as he senses the Holy Offering [the bread and wine], the sanctuary, the whole church, and the altar; and second, the priest recites it quietly during the Cherubic Hymn when he censes the altar, the sanctuary, and the people, just before the Great Entrance [when the gifts of bread and wine are shown to the people and brought back onto the altar]) and during the various cycles of prayer each day [Third Hour and Compline in particular]).
In addition to being a prayer of profound repentance, it is also a prayer of hope. We are reminded that God loves us, shows us His mercy, and invites us into union with Him in our lives now and for all eternity.
So, let us pray for each other today, that each day we have the strength, courage, and pleasure to pray:
Psalm 50 (51)
 Have mercy on me, O God, according to thy steadfast love; according to thy abundant mercy blot out my transgressions.  Wash me thoroughly from my iniquity, and cleanse me from my sin!  For I know my transgressions, and my sin is ever before me.  Against thee, thee only, have I sinned, and done that which is evil in thy sight, so that thou art justified in thy sentence and blameless in thy judgment.  Behold, I was brought forth in iniquity, and in sin did my mother conceive me.  Behold, thou desirest truth in the inward being; therefore teach me wisdom in my secret heart.  Purge me with hyssop, and I shall be clean; wash me, and I shall be whiter than snow.  Fill me with joy and gladness; let the bones which thou hast broken rejoice.  Hide thy face from my sins, and blot out all my iniquities.  Create in me a clean heart, O God, and put a new and right spirit within me.  Cast me not away from thy presence, and take not thy Holy Spirit from me.  Restore to me the joy of thy salvation, and uphold me with a willing spirit.  Then I will teach transgressors thy ways, and sinners will return to thee.  Deliver me from bloodguiltiness, O God, thou God of my salvation, and my tongue will sing aloud of thy deliverance.  O Lord, open thou my lips, and my mouth shall show forth thy praise.  For thou hast no delight in sacrifice; were I to give a burnt offering, thou wouldst not be pleased.  The sacrifice acceptable to God is a broken spirit; a broken and contrite heart, O God, thou wilt not despise.  Do good to Zion in thy good pleasure; rebuild the walls of Jerusalem,  then wilt thou delight in right sacrifices, in burnt offerings and whole burnt offerings; then bulls will be offered on thy altar.