The existence of the devil as a personal reality, and not merely as a symbol of evil, is an article of faith (Ott, Fundamentals 126-131; CCC 395, 2851). Denial of an article of faith is an element of the canonical crime of heresy (1983 CIC 751), an act punishable by measures up to and including excommunication, dismissal from the clerical state, and/or loss of ecclesiastical office (1983 CIC 1364, 194).
Rev. Arturo Sosa, sj, superior general of the Society of Jesus, denies the personal reality of the devil, describes him instead as a symbol of evil, and has expressed such views before (CNA article here, Catholic Herald article here). Protestations of Sosa’s orthodoxy by Jesuit spokesmen notwithstanding, Sosa speaks for himself, and clearly. I think his remarks warrant response, not just from bloggers and scholars, but from those placed in authority over such matters.
There are, I grant, some practical problems: the term “heresy” has been thrown around too loosely for some decades (perhaps for some centuries), the sanctions of excommunication and removal from office are themselves very weighty, and the latae sententiae (automatic) procedures by which such consequences are supposedly visited upon offenders are controversial in theory and practice, such that few in ecclesiastical leadership (including most orthodox members thereof!) wish to “pull the trigger” in such cases and, as a result, utterances such as Sosa’s provoke little, usually no, response from Church leaders with inevitable harm to the faithful.