Proslavery theologians based their claims to legitimacy on Scripture, but Lincoln denounced this position as incompatible with true religion, reason, and republicanism. He envisioned instead a united nation that would honor both God and American political principles. Fornieri casts Lincoln's unique combination of politics and piety as "biblical republicanism"—a merging of Judeo-Christian beliefs and the founders' tradition of self-government. In a time of unprecedented crisis and upheaval, biblical republicanism provided Lincoln with a moral justification for difficult political choices. Fornieri demonstrates the sincerity of Lincoln's belief and reveals the remarkable consistency between his public and private religious views. Though Lincoln's faith deepened during the turbulent war years and after the death of his son, Willie, his articulation of this faith remained consistent throughout much of his life. Convinced that religion was a crucial aspect of life, Lincoln maintained that his own faith guided and shaped his political thought. In contrast to scholars who have emphasized the Lyceum Address as the key to understanding Lincoln's religion and politics, Fornieri brings forth the Peoria Address of 1854 as a more profound and mature reflection of Lincoln's political faith. At Peoria, Lincoln invoked the Declaration of Independence as the nation's moral covenant, characterizing the struggle over extending slavery as a clash between rival political faiths. He emphasized that the Union was worthy of preservation in light of the Declaration's principles of liberty and equality, and that these principles were best secured under the auspices of national Union committed to the Constitution. sheds new light on how the Great Emancipator's personal trust in a living God shaped his vision for a new America.