This book is about thought—not the basic thought that we use to determine what to eat or wear or buy—but the Free Thought we use to make personal choices about the higher things of life: faith or unbelief, justice, morality, and the development and use of our creativity. Free Thought can have any outcome, including unbelief or faith, which is defined here as personal belief and trust in God, not as a religious affiliation. Free Thought is founded on free will. Everyone is a unique combination of a material body-mind and a spiritual soul. Free Thought is the integrated and iterative processing of information from the material and spiritual realms, in one or more common nonmaterial formats, across a mind-soul interface. Through our Free Thought, God and the spiritual force for evil change us and we change the material realm. All truthful spiritual insights and truthful disclosures through mathematics and science come from God, and it is through faith and science that we approach one whole body of truth. Free Thought, Faith, and Science includes definitions of terms, summaries of the author’s beliefs and background, a literature review, and a questionnaire for readers. It’s a comprehensive and thought-provoking book that will contribute to bringing more believers and nonbelievers together in an expansion of the faith-science quest for truth.