Vatican City, Nov 10, 2017 / 05:18 am (CNA/EWTN News).- In a key speech on the global effort to eradicate nuclear arms, Pope Francis called the weapons immoral and said they should be made illegal in war, but he also voiced hope that despite pessimism, things are moving in the right direction.

In a Nov. 10 audience with participants in a Vatican symposium on nuclear disarmament, the Pope said “a healthy realism continues to shine a light of hope on our unruly world,” particularly on the nuclear front.

Pointing to the international treaty passed at the United Nations in July, Francis said this is a concrete sign that progress is being made in the effort to eliminate nuclear arms, and called the treaty “a historic vote,” in which the majority of the international community “determined that nuclear weapons are not only immoral, but must also be considered an illegal means of warfare.”

The employment of nuclear devices, whether intentionally or through accidental detonation, he said, would cause “catastrophic humanitarian and environmental effects.”

Organized by the Pontifical Council for Integral Human Development, the Nov. 10-11 symposium is the first global gathering on this topic since the approval of the Treaty on the Prohibition of Nuclear Weapons at the United Nations July 7.

Until the treaty, nuclear weapons were the only weapons of mass destruction not explicitly banned by any international document. As the Pope pointed out in his speech, chemical weapons, biological weapons, anti-human mines and cluster bombs had all been explicitly prohibited in previous international conventions.

He praised the treaty as also being largely the result of humanitarian initiatives sponsored by the collaboration of civil society, states, international organizations, churches, academies and experts.

Ultimately, to achieve a world without nuclear weapons requires a change of heart, not just laws, he said, saying we must renew our focus on the integral development of the human person as an “indissoluble unity of soul and body, of contemplation and action.”

This approach gives hope that it's possible, the Pope said, adding that the perspective goes contrary to our own pessimism and the criticisms of those who see the effort to totally eliminate weapons of mass destruction as “idealistic.”

Quoting St. John XXIII's 1963 encyclical “Pacem in Terris,” Francis said, “unless this process of disarmament be thoroughgoing and complete, and reach men’s very souls, it is impossible to stop the arms race, or to reduce armaments, or – and this is the main thing – ultimately to abolish them entirely.”

Reiterating the many statements he's made on the topic, Pope Francis said the escalation of the arms race and the expense it requires means money is taken away from what should be the real priorities: “the fight against poverty, the promotion of peace and the undertaking of educational, ecological and healthcare projects.”

As a permanent observer to the United Nations, the Holy See has played an integral role in the negotiations of the treaty banning nuclear weapons. This role has included casting a procedural vote on the treaty earlier this year, which is a right the Holy See doesn't have for every issue, further underlining the their concern regarding nuclear weapons.

During talks on nuclear weapons at the U.N. headquarters in New York, Pope Francis said the treaty, which was still being negotiated at the time, was inspired by “ethical and moral arguments,” and was an “exercise in hope.”

On that occasion, he voiced his hope that the treaty would be “a decisive step along the road towards a world without nuclear weapons.” And while this is “a significantly complex and long-term goal, it is not beyond our reach.”