A.W. Tozer emphasizes the significance of both belief in the heart and confession with the mouth as essential components of salvation. He explains that public confession is a vital step in joining the church and fostering fellowship among believers. Tozer highlights Romans 10:8-10, illustrating that true faith involves both internal belief and external proclamation of Jesus as Lord. He urges those who have not experienced spiritual rebirth to recognize the importance of this confession, likening Jesus to the door of the ark that leads to salvation. The sermon calls for a genuine commitment to faith and community in Christ.