The Vatican has criticised one of the leading proponents of liberation theology, Father Jon Sobrino, a Basque who lives in El Salvador.
Pope Benedict XVI has been a staunch opponent of liberation theology
It says his writings give too much emphasis to Jesus Christ as a mortal man and are "erroneous or dangerous".
The warning comes ahead of a visit by Pope Benedict XVI to Brazil in May.
Liberation theology is a strand of Catholicism popular among the poor in Latin America, and often associated with left-wing politics.
Father Sobrino speaks about Jesus in his writings as someone the common man could relate to, "our brother in relation to God".
Pope Benedict XVI is well known as an opponent of liberation theology.
In 1985, when he was a Cardinal, he censured Brazilian friar Leonardo Boff for promoting Marxist ideas.
In a note about Father Sobrino's writings, the Vatican said: "These works contain propositions which are either erroneous or dangerous and may cause harm to the faithful".
A papal censure can make a book virtually taboo in Catholic countries.
Benedict XVI will visit Brazil from 9 to 13 May.