The object of this book, the author indicates, is not a ""proved"" Christianity nor a ""disproved"" humanism, but an examination of the alternatives to the former--and to some extent, to the latter as well. The systems, or, at least organizing attitudes, of belief treated include humanism; evolutionary optimism and pessimism (Teilhard de Chardin is taken as exemplar of the former); Utoplanism--especially of the Marxian kind (which the author distinguishes from Communism); Existentialism; Psychology, ranging from behaviorism through Freud and Jung; and Positivism, including its latest exponents in logical positivism. These options are discussed with sound, although necessarily compressed, knowledge and insight. The inroads of these various systems into the Christian church is regarded by the author as the sign of the degree to which the church has been penetrated by secularist and humanist thought. ""Is it possible,"" he asks, ""against the tide of all that research, scholarship and hostile analysis to say (ever again) what Christianity is?"" He attempts an answer, and may be forgiven if it is not a wholly convincing one. First delivered in substance as lectures at Kenyon College, the contents of this book will provide instructive and sobering reading for a wide variety of concerned persons.