A.B. Simpson emphasizes that true humility comes from being born again through Christ, as humanity has lost its original simplicity and approachability. He encourages Christians to embody a childlike spirit, being relatable and loving towards others, rather than becoming stiff and self-conscious. Simpson illustrates this with the example of Christ, who approached people with genuine humanity and love, demonstrating that it is through simple acts of kindness that we can connect with others and lead them to salvation. The sermon calls for believers to seek a heart like Christ's, one that is warm and inviting, to effectively reach out to those around them.