John Gill preaches on the eternal union of God's elect with Him, emphasizing that this union is rooted in God's love and is an eternal act of grace. He explains that this union encompasses adoption, justification, and acceptance, all of which are established in Christ before the foundation of the world. Gill highlights the various aspects of this union, including election, conjugal, federal, and legal unions, illustrating how they reflect the deep and unbreakable bond between God and His chosen people. He reassures believers that nothing can separate them from God's love, affirming their secure position in Christ. Ultimately, this union is foundational for understanding the blessings of grace bestowed upon the elect.