Psalm 50 (English Bibles, 51) is the only Psalm prescribed to be recited in its entirety during every celebration of the Divine Liturgy. Whether in the Liturgy of St Basil or St John Chrysostom, it is the prayer of a murderer and adulterer that the Priest must pray when the congregation commences chanting the Cherubic Hymn in preparation for the Great Entrance of the Holy Gifts. It is a Psalm in which, using the words of that great sinner David, one prays for God’s Holy Spirit, mercy and forgiveness.
It is this strong sense of the presence of the Holy Spirit that keeps this Psalm from being despairing. The Holy Spirit spoken of by David also, as St Luke writes in the Acts of the Apostles, is the same which descended on the day of Pentecost upon the disciples after the Lord’s Ascension. “Cast me not away from Your presence, and take not Your Holy Spirit from me” (v. 11). From this verse, the Church has taken one of the most common and most encouraging petitions. If we ask that the Holy Spirit may not be taken from us, it follows that we must have received Him. We receive the Holy Spirit as Orthodox Christians in the Sacrament of Baptism.
We learn clearly from these words that David was not deprived of the Grace of the All-Holy Spirit: it is not as though he asks to recover it after being deprived of it; rather, he begs not to be deprived of it, nor kept far from the Divine Care of God. “Restore to me the joy of thy salvation, and uphold me with a willing spirit” (v. 12). What David had not lost he begs to retain, that is, the Grace of the Spirit.
What he had rejected he asks to recover; this is joy in the Lord. King David enjoyed every satisfaction, he is saying, when he had great confidence in the Lord, whereas now that he is deprived of it, he is also deprived of joy. It was slavery to pleasure, however, which robbed him of joy. Hence David begs that his mind may recover the former guidance, and after being subject to the passions it may once more regain control over them.
Source: Lychnos June – July 2017