Mere Christianity is C. S. Lewis' forceful and accessible doctrine on Christian belief. First heard as informal radio broadcasts and then published as three separate books- The Case for Christianity, Christian Behavior , and Beyond Personality-Mere Christianity brings together what Lewis sees as the fundamental truths of his religion.

Rejecting the boundaries that divide Christianity's many denominations, C. S. Lewis finds a common ground on which all those who have Christian faith can stand together, proving that "at the center of each there is something, or a Someone, who against all divergences of belief, all differences of temperament, all memories of mutual persecution, speaks with the same voice."