Samuel Logan Brengle emphasizes the necessity of having an undivided heart in the pursuit of soul-winning, arguing that a divided heart cannot effectively lead others to true repentance and a relationship with Jesus. He illustrates that the soul-winner's task is profound, requiring complete dedication and abandonment to God's work, akin to the commitment shown by great figures in history. Brengle warns against distractions and the temptation to retreat, urging that true success in ministry comes from a heart wholly devoted to God. He concludes by affirming that regardless of one's abilities or education, a perfect heart towards God is what He blesses, as seen in the scripture that highlights God's search for those whose hearts are perfect toward Him.