Complex sentence: The theory of the Cultural Revolution states that the proletarian revolution and the dictatorship of the proletariat does not wipe out bourgeois ideology--the class-struggle continues and even intensifies during socialism, therefore a constant struggle against these ideologies and their social roots must be conducted.
Split into simpler sentences: The theory of the Cultural revolution states that the proletarian revolution and the dictatorship of the proletariat does not wipe out bourgeois ideology; the class-struggle continues, and even intensifies, during socialism. Therefore, a constant struggle against these ideologies and their social roots must be conducted.