How does Hebrews define faith and demonstrate its power through the lives of the Old Testament saints?

The author opens his celebrated tribute by defining faith as the substantial foundation of things hoped for and the inward certitude of invisible realities, through which ancestral generations gained God's approval. By this virtue, believers perceive that the entire created universe was framed through the sovereign word of God, so that everything visible emerged from unseen origins. By faith, Abel offered a sacrifice far more acceptable than Cain's, receiving divine testimony to his righteousness through God's favor upon his gifts, so that though dead, his witness continues to speak. By faith, Enoch was translated without tasting death, having received the witness that he pleased God. The author declares that without faith it is impossible to please God, because whoever approaches the divine presence must believe that He exists and that He rewards those who earnestly seek Him. By faith, Noah reverently heeded divine revelation concerning unseen impending judgments, constructing an ark to preserve his household, thereby condemning an unbelieving generation and inheriting the righteousness that flows from faith.

Hearing God's command, Abraham obediently departed for an unknown land of inheritance without knowing his destination, dwelling as a pilgrim in cottages alongside Isaac and Jacob, his coheirs in the divine promise. His gaze was directed toward an eternal city resting on solid foundations, whose architect and creator is God alone. Through faith, barren Sarah received physical vigor to conceive despite her advanced years, trusting the fidelity of Him who promised; consequently, from a single man who was virtually dead sprang progeny as innumerable as the stars of the sky and the sands along the shore. All these holy souls died in steadfast faith without receiving the complete fulfillment of the promises, hailing them from a distance and confessing themselves as foreign travelers upon earth. Rather than longing for the temporal country they left behind, they yearned for a superior, celestial homeland, prompting God to acknowledge Himself as their God without shame and prepare an eternal city for their reception. When tested, Abraham offered Isaac, his sole heir of promise, concluding that God was powerful enough to raise him from the dead; as Challoner's gloss notes, Abraham received him back as a prophetic parable prefiguring Christ slain and resurrected.

The legacy of faith continued through succeeding generations. Isaac imparted prophetic blessings concerning future events upon Jacob and Esau, and dying Jacob blessed the sons of Joseph, venerating the summit of his staff. Challoner explains that the author follows the Septuagint rendering, interpreting Jacob's gesture as relative veneration offered toward Joseph's staff as a figure of Christ's royal majesty, and rejecting translators’ rendering of leaning upon his own staff as a corruption of the text. Dying Joseph gave commands regarding his bones in anticipation of the Exodus. By faith, Moses' parents concealed him for three months, undaunted by the royal decree. Reaching adulthood, Moses renounced his status as the son of Pharaoh's daughter, choosing to endure hardships with God's people rather than relish the fleeting pleasures of sin, regarding the reproach of Christ as far greater wealth than all Egypt's treasures. He abandoned Egypt without dreading the monarch's anger, persevering as one beholding the invisible King, celebrating the Pasch and sprinkling blood so that the destroyer would spare Israel's firstborn. By faith, the Hebrews crossed the Red Sea on dry ground while the pursuing Egyptians were swallowed, the ramparts of Jericho fell after going round them seven days, and Rahab the harlot was delivered because she received the scouts in peace.

The author observes that time would fail to recount the triumphs of Gideon, Barak, Samson, Jephthah, David, Samuel, and the prophets, who through faith subdued realms, executed justice, secured promises, closed the jaws of lions, quenched fierce fires, escaped swords, recovered strength from weakness, and routed foreign hosts. Women received back their resurrected dead, while other martyrs endured torture and rejected liberation to attain a superior resurrection. Others endured mockery, scourgings, chains, imprisonment, stoning, sawing asunder, and the sword, wandering destitute through wildernesses and caves, souls of whom the world was unworthy. Although all these ancients were authenticated through their unwavering faith, they did not receive the final realization of the promise during life, because God designed a superior dispensation for us, so that they should not attain ultimate perfection apart from our communion.