It was the ideology of the Rexist Party (Parti Rexiste), officially called Christus Rex, founded in 1930 by Léon Degrelle, a Walloon. The name was derived from the Roman Catholic social teachings concerning Christus Rex, and it was also the title of a conservative Catholic journal.
The ideology of Rexism called for the moral renewal of Belgian society in conformity with the teachings of the Church, by forming a corporatist society, and abolishing democracy. The Rexist movement attracted support mostly among the Walloons; it had a counterpart on the Flemish side in the Vlaamsch Nationaal Verbond, or VNV. Rexism soon began to ally itself with the interests of Nazi Germany and to incorporate Nazi-style antisemitism into its platform after Adolf Hitler's rise to power, and got financial support from German interests, while ties to the Roman Catholic Church were increasingly cut off one-sidedly by the Belgian bishops. Some former Rexists went into the underground resistance against Nazi Germany, after they had come to see the Nazis' somewhat anticlerical and very anti-Semitic policies enforced in occupied Belgium (although others, notably José Streel, simply withdrew from political activity as a result of this). Most Rexists however proudly supported the occupiers and assisted Nazi Germany in its battle against communism wherever they could.
Closely affiliated with Rexism was the Légion Wallonie, a paramilitary organization along the lines of the SS. After Operation Barbarossa started, the Legion Wallonie and its Flemish VNV counterpart, the Legion Flandern sent respectively 25,000 and 15,000 volunteers to fight against the Soviet Union.
With the fall of Nazi Germany in 1945, Degrelle took refuge in Francoist Spain. He was convicted of treason in Belgium and sentenced to death, but requests for Spain to extradite him were unavailing. Degrelle died in Málaga in 1994.