T. Austin-Sparks emphasizes the significance of 'full knowledge' in understanding the unsearchable riches of Christ, highlighting that this knowledge is not merely intellectual but a revelation from the Holy Spirit. He explains that the prefix 'epi' in the Greek signifies a deeper, mature understanding of God, which Paul prays for in his letters. Sparks outlines the major eras of God's revelation, from before time to the consummation of the age, and stresses the centrality of Christ in God's eternal purpose. He asserts that true knowledge of God is rooted in the eternal counsels of the Godhead, where the Son was appointed as the sphere of all that belongs to God. Ultimately, the sermon calls believers to seek a deeper, Spirit-led understanding of their faith.