The author traces the development of Abraham Lincoln's religious life from youth through his public career, situating beliefs within historical and social contexts and treating religion as part of lived experience rather than mere theological opinion. He compiles and critically evaluates published and personal testimony, opens new lines of evidence, and assesses the credibility of conflicting accounts to move beyond polemic. The study links changing convictions to personal and cultural influences and concludes with a reasoned interpretation of Lincoln's faith while providing readers with evidence and analysis to form their own judgments.