A Saturday afternoon mass at the Sacred Heart Cathedral turned violent when 48-year-old Charles Miller walked to the alter and punched Bishop Manuel Cruz during a prayer.
According to North Jersey, Essex County authorities charged Miller with assault. They declined comment on a possible motive for the attack.
The mass was in honour of baseball Hall of Famer Roberto Clemente, who died in a 1972 plane crash as he flew to Nicaragua to deliver aid to earthquake victims.
Cruz was taken to hospital and his injuries were not serious.