T. Austin-Sparks emphasizes the prophetic warnings in the letter to the Hebrews regarding a future great shaking that will test the foundations of faith and reveal the true nature of spiritual life in Christ. He argues that this shaking is necessary to remove what is unshakable and to establish a kingdom that cannot be moved, highlighting the need for a deeper understanding of Christ as the standard of judgment. Sparks warns against the dangers of conforming Christianity to worldly standards and the illusion of success, urging believers to seek genuine spiritual depth rather than mere outward appearances. He calls for a return to waiting upon God and discerning His methods, as the shaking will reveal the true essence of faith and the presence of Christ in our lives. Ultimately, the sermon serves as a call to spiritual vigilance and growth in the face of impending trials.