John Gill expounds on 1 John 5:8, emphasizing the three witnesses on earth that testify to the truth of Christ's sonship: the Spirit, the water, and the blood. He clarifies that the Spirit refers to the Gospel and the Holy Spirit's work in believers, while the water symbolizes baptism as a public declaration of faith, and the blood represents the Lord's Supper and the martyrdom of believers. These witnesses collectively affirm the truth of Christ's divine sonship and are unified in their testimony. Gill illustrates the harmony between the Gospel and the ordinances, highlighting their central focus on Christ.