* Honduran cardinal openly criticises CDF head as too rigid
* Mueller seen out of step with pope's reform trend
* Cardinal says he, pope baffled by German "luxury bishop"
By Tom Heneghan, Religion Editor
PARIS, Jan 20 (Reuters) - An influential aide to Pope Francis criticised the Vatican's doctrinal watchdog on Monday and urged the conservative prelate to be more flexible about reforms being discussed in the Roman Catholic Church.
Cardinal Oscar Rodriguez Maradiaga, the head of a "kitchen cabinet" the pope created to draw up reform proposals, said that Archbishop Gerhard Mueller - who has opposed any loosening of Church rules on divorce - was a classic German theology professor who thought too much in rigid black-and-white terms.
"The world isn't like that, my brother," Rodriguez said in a German newspaper interview, rhetorically addressing Mueller in a rare public criticism among senior Church figures.
"You should be a bit flexible when you hear other voices, so you don't just listen and say, 'here is the wall'," Rodriguez said in an interview with the daily Koelner Stadt-Anzeiger.
Rodriguez, archbishop of the Honduran capital Tegucigalpa, did not cite any possible reforms in particular but said the pope's critics, such as those upset by his attacks on capitalism, were "people who don't understand reality."
Former Pope Benedict picked Mueller in 2012 to head the Congregation for the Doctrine of the Faith (CDF), the successor office to the Inquisition. Benedict ran that office as a powerful and feared guardian of Church orthodoxy for 24 years as Cardinal Joseph Ratzinger, until he was elected pope in 2005.
But its influence has waned under Francis, who soon after his March 2013 election was reported as telling visiting South American priests and nuns not to worry if the CDF wrote to them criticising what they were doing.
NO TO CHANGING DIVORCE RULE
In an article in the Vatican daily last October, Mueller firmly rejected growing demands for divorced and remarried Catholics to be reinstated as full members of the Church.
Catholics who divorce and remarry in a civil ceremony are excluded from communion because the Church teaches that Jesus declared marriage an indissoluble bond.
With divorce on the rise, more Catholics are asking Rome to show mercy for them. German bishops have been in the forefront of reform thinking and one archdiocese even published guidelines on how to readmit them, which prompted Mueller's article.
The Vatican is due to consider reforming its rules on divorce at a worldwide synod of bishops next October.
Mueller has also strongly defended Bishop Franz-Peter Tebartz-van Elst, who reaped stiff criticism from German Catholics and the title "luxury bishop" in the media after it was revealed he spent at least 30 million euros ($40.69 million) on a new residence complex.
Tebartz-van Elst's grand plans were so far from the modest approach favoured by the Argentine-born pontiff that Rome sent an envoy to inspect his diocese and later sent him off to a monastery for a leave of absence pending a final decision.
Rodriguez did not think Tebartz-van Elst would return to Limburg and said Latin Americans like himself and the pope found it hard to understand spending so much money for opulent features such as a 15,000-euro free-standing bath tub.
"For most people, a shower and a toilet are enough," he said. "They're enough for the pope in his three-room apartment too." ($1 = 0.7373 euros) (Editing by Robin Pomeroy)