Chavez's reform plan, which will be voted on in a December referendum, also includes allowing security forces to detain Venezuelans without charge during political ''emergencies'' or major natural disasters.
Polls show Chavez will likely win the referendum because the proposal also includes popular moves such as shortening the workday and extending social security benefits to street vendors as he turns the OPEC nation into a socialist state.
In an open letter to Venezuelans, the Church urged voters to carefully weigh the ''difficult decision'' in December.
''The reform has been presented as though it is a tool to give the people more power ... It offers a reduced workday and holds out highly-prized social security to informal workers,'' said the Episcopal Conference, the Church's highest body in Venezuela.
''However, it accentuates the concentration of power in the president's hands and favors authoritarianism.'' Chavez wants to scrap term limits for the president but not for any other elected official.
The Church is one of the few respected, independent institutions in Venezuela and has repeatedly clashed with Chavez since he came to power in 1999.
It criticizes his leftist policies and has called on him to tone down his often aggressive rhetoric. In response, the former soldier, who remains popular due to his spending of oil income on the poor, portrays them as elitists who backed a failed coup against him in 2002.
Chavez is a close ally of Cuban leader Fidel Castro and has promised a socialist revolution to end poverty and roll back the influence of the United States in Latin America.
Venezuelans are overwhelmingly Roman Catholic but they generally practice their faith less than their counterparts in other Latin American countries such as Mexico or Brazil.
REUTERS RKM BST0059