Psalm 51 is a cry of King David’s heart and a plea to God for mercy:
“10 Create in me a pure heart, O God,
and renew a steadfast spirit within me.
11 Do not cast me from your presence
or take your Holy Spirit from me.
12 Restore to me the joy of your salvation
and grant me a willing spirit, to sustain me.”

David, a most powerful king, is powerless to cleanse, revive and sustain himself. David knows and feels his need for God’s presence to cleanse him, renew his faith, restore his joy, and enable him to persevere. By God’s Spirit, he trusts in the mercy of God’s redeeming love. Like David, we can invite God’s presence in and our souls be transformed. It may be a process of cleansing and renewing, but His Spirit brings restored joy and a strengthened, sustained spirit.