Karl Kautsky is probably the first Marxist to interest himself both in the movement and the enigmatic personality of the crucified prophet. His 1908 book The Foundations of Christianity is a rather impressive attempt at a Marxist analysis. The book is rather original, innovative and has been rranslated into nine languages. Kaustky made his Foundations of Christianity into one of the most popular Marxist theoretical works. Its popular success is probably due to the interest of socialist militants to see a vision of the origins of Christianity which permits the modern workers' movement to appropriate to itself the figure of Jesus as a prophet and martyr for the proletarian cause.

Kautsky wanted to interpret early Christianity as a precursor of the contemporary working class socialist movement. His friend, and later his opponent, Rosa Luxemburg, in an article of 1905 called "The Church and Socialism insisted that the first Christian apostles were Communists who denounced injustice and the cult of the Golden Calf". He counterposed a materialist account of the new religion against the Christian mythology and showed the capacity of the Marxist method to give an account of a complex historical process, interpreting a religious phenomenon in terms of the class struggle.

The book is divided into four sections:

1) Society at the time of the Roman Empire: the slave economy, the absolutist forms of the state, the different manifestations of cultural and religious crisis.

2) Judaism: the class conflicts of Israelite society and the various political-religious currents (Sadducees, Pharisees, Zealots and Essene.

3) The beginnings of Christianity: the early Christian communities, the idea of the messianic Christ and Christian communism.

4) The fourth section is dedicated to the "personality of Jesus".

According to Kautsky, what distinguishes Jesus' messianism from the other rebellious Jewish prophets of the era - all of whom had a strictly national character - is