NOTES for Mar 1:7-8
Speaking of the coming Messiah, Mark mentions washing "with the Holy Spirit." What does he mean? And why was such a washing impossible in pre-Christian times? Did God's breath not fill the world then just as it does now? Of course it did. All the prophets of Israel spoke of the breath of YHWH (of the Spirit of the Lord), and the movement of this breath was undoubtedly familiar to them. And yet there is something special in the washing with God's breath of which John speaks.
What were cleansing washings in pre-Christian times? They were part of a rite of purification, the part with which that rite began. It was thought that impurity stained a person both from the outside and from within, and that one had to be cleansed from it both outwardly and inwardly. Ritual washings were used for outward cleansing: water, people thought, carried away everything from which a person wanted to cleanse himself, his body, and his life. But this was not enough: the cleansing washing was always followed by a special purifying sacrifice, and here, through sprinkling with sacrificial blood consecrated by God, the person was cleansed already from within. God's presence, of course, also sanctified the body already washed with water, but most of all it sanctified the soul and heart, freeing them from the consequences of a committed sin or of contact with uncleanness. But such cleansing, alas, did not guarantee freedom from sin in the future.
Meanwhile, in the Kingdom of the Messiah there can be no place for sin. To become its inhabitant, one must be completely changed, become so alien to sin that it will never again enter the life of the one seeking the Kingdom.
This, of course, is beyond the strength of fallen humanity. But what is impossible for man is possible for God and for the Messiah sent by Him. He can wash a person not with water and not with sacrificial blood, but with that breath of God which can not only cleanse a person, but completely transform him. This transformation becomes, for the one seeking the Kingdom, the final cleansing washing and the final sanctification: a washing and sanctification after which there will no longer be room for sin in his life. At least to the extent that this life will belong to the Kingdom.