The noted religious historian and anthropologist was 92.
In a message to Bishop Guy Harpigny of Tournai, the Pope described the late prelate as an “eminent man of faith who faithfully served the Church.”
“Through education and research, particularly in the field of history of religions of which he was an acknowledged expert, he always had the desire to testify to his faith among his contemporaries, in a spirit of dialogue,” the Pope wrote.
Being over 80 years of age, Cardinal Ries was not among those voting for a new Pope now.
His death leaves the number of cardinals worldwide at 208.
Cardinal Ries was born in 1920 at Fouches, Belgium, and ordained priest in 1945.
Days before Pope Benedict elevated him as cardinal on Feb. 18, 2012, he was consecrated bishop.