Who shall ascend the hill of the LORD?
And who shall stand in his holy place?
He who has clean hands and a pure heart,
who does not lift up his soul to what is false
and does not swear deceitfully.
He will receive blessing from the LORD
and righteousness from the God of his salvation.
(Psalm 24:3-5 ESV)
Worship is not for those who want the blessing of God at the same time they want to hang on to their sins. Worship is for clean-handed people, for pure-hearted people. This is why, in response to God when He calls us to worship Him, we quickly move to confession, where we wash our hands and hearts. God has a blessing for those that Jesus washes in the bloody water of baptism. He offers us a white robe of righteousness in exchange for our filthy rags. But the muck on our hands would instantly spoil such a robe, and the impurity of our hearts would leach through and defile holy clothes. So we come to Jesus for washing, so that we can ascend the holy hill in cleanliness and purity, eager to receive the blessing that the Lord promises us.