- What It Is 2. What It Does 3. For Whom It Is Opened The sermon interprets Zechariah 13:1 as a prophetic reference to the fountain of cleansing opened through the pierced side of Jesus Christ. It explains that this spiritual reality addresses both the guilt and the filth of sin, fulfilling the Old Testament types of purification with water and blood. The preacher emphasizes that believers must approach this fountain by faith, recognizing their need for both pardon and ongoing sanctification. Ultimately, the message calls repentant sinners to mourn over their sins and rest in the grace provided by God's sacrifice.