Complex sentence: It was formed in 1971 by Alfredo Maneiro, an intellectual and one-time Communist Party of Venezuela guerrilla, who believed that the Communists and the Movement towards Socialism were not serious enough about organizing the working class as a revolutionary force.
Split into simpler sentences: It was formed in 1971 by Alfredo Maneiro, an intellectual and one-time Communist Party of Venezuela guerrilla. Maneira believed that the Communists and the Movement towards Socialism were not serious enough about organizing the working class as a revolutionary force.