In the first reading we ask God to cleanse us of all impurities, and we ask him to give each of us a new heart, and to put a new spirit in us.
The one thing preventing him from cleansing us from our impurities and from giving us new hearts is our own unwillingness to cooperate with him in this.
God cannot cleanse us from impurities if we cling to them. He can’t give us new hearts if we won’t let go.
He has spread a banquet before us, but his choice dishes can do nothing for us if we ignore his invitations.