SINGAPORE - Every global challenge in the 21st century demands that countries and people resist hatred and exclusion, said Jordan's King Abdullah II, who also made the call for the world's "single most" important threat to be tackled - the attack on interfaith harmony, mutual respect and trust.

"Economic growth, peacemaking, protecting the environment, global security, inclusive opportunity - all these critical goals require that we cooperate, and combine our strengths to our common benefit," he said on Thursday (June 20) at an international conference on interfaith understanding and social cohesion.

King Abdullah, a global leader in promoting interfaith understanding and dialogue, spelled out three areas which warrant special attention: Gathering together those who seek peace and harmony; taking advantage of the tools of the modern world; and making a commitment for the long term.

He was speaking at the inaugural International Conference on Cohesive Societies held in Singapore. Around 1,000 academics, government officials and members of religious and civil society groups from close to 40 countries are attending the three-day summit.

The event opened on Wednesday with a dinner and opening address by Singapore's President Halimah Yacob.

King Abdullah delivered a keynote address to kick off Thursday's discussions, which include plenary sessions on the role of faith in inter-religious relations, and how societies can promote shared identity and encourage empathy.

Noting the recent attacks in Christchurch, New Zealand, and Sri Lanka, and other terrorist acts around the world, King Abdullah said in his nine-minute speech that they showed the evil that extremists will do to drive people and societies apart.

"But we must also see, clearly, the tremendous power we have, as a united world, to defeat these evils and secure the future our peoples deserve," he added.

He called on people who seek peace and harmony to rally together, and listed "The Amman Message" and "A Common Word" as two Jordanian initiatives which have inspired positive exchanges worldwide.

Issued in 2004, The Amman Message underlines the key principles of tolerance, moderation and dialogue that Islam teaches, while A Common Word is an interfaith initiative promoting peace and cooperation between Muslims and Christians.

King Abdullah also gave the example of the Jordanian-sponsored United Nations initiative - the annual World Interfaith Harmony Week - which encourages dialogues of mutual respect.

To defend global cohesion, he said people should take advantage of the tools of the modern world.

"Now extremists have manipulated today's global connectivity to plot, recruit, arm, and publicise their dark atrocities. We must do better," King Abdullah added, noting two measures that have been taken to address the issue.

He pointed to the Aqaba Process, a multi-national meeting started by Jordan in 2015 to strengthen cooperation in the fight against terrorism and extremism, and the Christchurch Call initiative, to rally governments and firms to commit to steps to deal with hateful and extremist content posted online.

"But solutions are not exclusively the job of governments and big companies. In a very real way, the Internet belongs to its users. Moderate, positive voices need to reclaim this space and redirect the dialogue away from misinformation, insults and fear, and towards understanding and respect," he said.

"Young men and women have a vital role in speaking up on social media and social networking sites, and using their talent for innovation to promote mutual understanding and hope," he added.

King Abdullah said that the world faces a complex and evolving threat to cohesion, and tackling it requires a long-term commitment.

"Meeting it demands an holistic approach addressing security and also the issues that extremists exploit," he added.

"And that means investing in inclusive, sustainable development, so that all people - especially the young people - can share in opportunity, fighting the war of ideas to combat divisive ideologies, and then responding to the world's unprecedented refugee crisis."

King Abdullah also called for lasting peace to the Palestinian-Israeli conflict, which has fuelled global discord and radicalism.

He said it should meet the need of both sides: a viable, independent and sovereign Palestinian state on the 1967 lines - with East Jerusalem as its capital - but living side by side with Israel in peace and security.

"And we must safeguard Jerusalem, a holy city to billions of people around the world... Jerusalem should be, and must be, a unifying city of peace," he added.

The conference is organised by the S. Rajaratnam School of International Studies at Nanyang Technological University, with the support of the Ministry of Culture, Community and Youth.