Following Tuesday's mass killing at a care home in Japan for persons with mental disabilities, one of the country's bishops has said the incident demonstrates the need for such persons to be valued and protected by society.

"Disabled people have to be protected," Bishop Tarcisio Isao Kikuchi of Niigata told CNA.

He added: "A society which will not protect the weak has no respect for human dignity."

In the early hours of July 26 an attacker entered the Tsukui Yamayuri-en facility in Sagamihara, some 20 miles northwest of Yokohama, stabbing 19 people to death. The dead ranged in age from 19 to 70, and another 25 people were wounded.

Shortly after the attack, 26-year-old Satoshi Uematsu, a former employee of the care center, turned himself in to local police and was arrested.

Uematsu had written a letter to Japan's parliament in February advocating for euthanasia of persons with disabilities, saying it would be better if they "disappeared."

"My goal is a world in which the severely disabled can be euthanised, with their guardians' consent, if they are unable to live at home and be active in society," he had written.

In that letter Uematsu had threatened to kill hundreds of disabled persons, according to Kyodo news agency. After delivering the letter, he was kept in a hospital for nearly two weeks before being released.

Bishop Kikuchi condemned the attack, saying it was "a serious attack against human life and human dignity, which we believe to have the greatest value of all."

He expressed hope that after "this sad incident the general public of Japan would have a chance to consider the importance of human dignity and the importance of providing support to the weak in society."

Such mass killings are extremely rare in Japan, which has strict gun control laws. The last was in 2008, when a man stabbed seven people to death in a Tokyo shopping district.

Bishop Kikuchi said, "I am just unable to find any words to express my shock and sorrow upon hearing the new of the mass stabbing … I am so sorry to the families of the victims and hope that they would receive the necessary support."

He also voiced concern over the low wages earned by employees of care centers like  Tsukui Yamayuri-en, and said Japan's system of protecting its weakest "needs to be revisited."

The bishop also said that among the factors influencing deteriorating values in Japan is that the country's "traditional family system is quickly disappearing, and that is strongly affecting the value afforded to human life."

He asserted that since World War II, the citizens of his country have pursued "material success, and after several recessions in the past 20 years, the general feeling of the public is always that our dream days, like the '70s and '80s, would come back again."

"So the standard of value in society is based on monetary gain and because of the past 20 years' recessions, many young people have … lost hope for the future," Bishop Kikuchi lamented.

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He also stated that education in Japan "in the past 70 years has managed to keep young people away from traditional religious values. Religion is something very foreign to many youth in Japan, and the absence of God does not contribute to establish a morals-based value system in our society."