John Wesley preaches about the 'Wilderness State' that believers often experience after being delivered from sin, likening it to the Israelites' wandering in the wilderness. He emphasizes that this state is characterized by a loss of faith, love, joy, and peace, leading to spiritual darkness and powerlessness. Wesley identifies the causes of this condition as sin, ignorance, and temptation, and he stresses the importance of self-examination to find the root cause of one's spiritual malaise. He encourages believers to seek restoration through repentance and a renewed commitment to prayer and obedience to God. Ultimately, Wesley reassures that God desires to restore joy and peace to those who earnestly seek Him.