Cerezo was born in Guatemala City, the son of the Supreme Court judge Marco Vinicio Cerezo Sierra, and came from a well-known liberal family. In 1962 he was a member of the student body of the Universidad de San Carlos de Guatemala (USAC) that played an important part in the national protests against the government of Miguel Ydígoras. In 1964 he joined the Guatemalan Christian Democrats (DCG), a party that was banned from standing in the 1966 elections. He graduated in Judicial science from USAC in 1968, the same year in which the DCG was formally legalized, and was made its Secretary in 1970. From that time, and with a very tense political situation, Cerezo was forced to hire permanent protection. In February 1981, in the worst of 3 assassination attempts, his vehicle was attacked with hand grenades and machine gun fire in the center of the capital.
In 1974 the DCG formed part of the coalition that backed General Efraín Ríos Montt for President. Amidst allegations of fraud Ríos Montt lost to Kjell Eugenio Laugerud. Cerezo was elected a deputy in the National Congress where the DCG, with 14 seats, became the largest party within the opposition.
In 1978 General
Ricardo Peralta Méndez, the DCG candidate came second to Fernando Romeo Lucas García. During the Lucas García era 150 members of the DCG were murdered. The three surviving members of the Congress and the party were forced into hiding, not because of a ban but in fear of their lives. Yet Cerezo appeared at the March 1982 elections to support the opposition candidate Alejandro Maldonado Aguirre who lost out to the official candidate Ángel Aníbal Guevara. Suspecting fraud Maldonado and Cerezo and their followers launched a campaign denouncing the result. The result became academic when Efraín Ríos Montt took power in a coup, which the DCG and Cerezo initially supported. When it became clear that the repression in the countryside was becoming more indiscriminate, and, perhaps more importantly, that Ríos Montt was fanatically preaching an evangelical, messianic born again type of Christianity, Cerezo withdrew his support for the regime and demanded new elections. In 1983 General Óscar Humberto Mejía took power in another coup, which Cerezo cautiously supported. The DCG gained 21.2% of the vote in the 1984 National Congress elections, and with 20 of the 88 seats was the largest party. With this success behind them the DCG decided to postulate Cerezo for the 1985 presidential election. He began to promote the idea of talking to the United Guatemalan National Revolutionaries (URNG), an umbrella group containing the main three guerrilla groups.