Andrew Murray emphasizes the significance of united prayer among believers, highlighting that while personal prayer is essential, the collective agreement in prayer brings about a powerful presence of Jesus and answers from the Father. He illustrates that just as family members come together to express their desires to their father, Christians should unite in prayer, recognizing their shared relationship with God as 'Our Father.' Murray points out that true united prayer requires agreement on specific requests, gathering in the name of Jesus, and the expectation of answers, which can lead to profound blessings for the church and its members. He encourages believers to embrace the privilege of united prayer, as it can unleash God's power and hasten the coming of His kingdom. The sermon concludes with a heartfelt prayer for unity and the effectiveness of prayer within the church.