Over 5,000 Christians have gathered in South Korea for the Fourth Lausanne Congress on World Evangelization to strategise about how to fulfil the Great Commission.

The once in a generation congress is taking place across seven days at the Songdo Convensia in Incheon, a city bordering the capital of Seoul. Thousands more are participating in the congress virtually.

Delegates from over 200 countries will hear from over 50 speakers and contributors on key issues affecting the global church and missions today, including intergenerational ministry, emerging technology, and God's mission in cities, areas of conflict and persecution, and the workplace. Other sessions will reflect on the state of Korean Christianity and the situation in neighbouring North Korea.

Speakers include Dr Patrick Fung, Global Ambassador of OMF International, Purpose Driven Life author and pastor Rick Warren, Dr Billy Wilson, president of Oral Roberts University, and Egyptian professor Anne Zaki.

Lausanne 4 is taking place under the banner of 'Let the Church declare and display Christ together', with an emphasis on collaborative reflection and action.

Commenting on the Congress theme, Dr Fung, said, "A divided church has no message for a divided world. God has called us to a unity of the Spirit in the bond of peace."

Sharing the vision for the congress at the opening ceremony on Sunday evening, Lausanne global executive director, Dr Michael Oh, said that as evil becomes "more vocal and visible in the world", now is not the time for the Church to "cower" or retreat but rather to declare and display Christ in faith.

"Not arrogantly but humbly. Not in competition but in collaboration," he said.

Dr Oh laid bare the scale of the challenge as he told delegates that the task of sharing the Gospel with the whole world remains "challenging" despite "an incredible amount of good Gospel work" in the half century since the first Lausanne Congress in Lausanne, Switzerland, in 1974.

He said, "In the last 50 years, over 9,000 unreached people groups have been reached with the Gospel. We've seen incredible growth in the Church in Africa, Asia and Latin America. We've seen new evangelistic strategies and theologies and methodologies developed.

"But with the explosion of population growth in many of these same areas of the world, the trajectory is not an acceleration of the sharing of the Gospel but a deceleration."

Later he added, "Eighty-six per cent of every Muslim, Buddhist, and Hindu in the world do not know a single Christian."

This Lausanne congress differs from previous ones in its emphasis on training and equipping Christians to be witnesses to the Gospel in their places of work. Dr Oh said that the global Church would be "ninety-nine times more effective" if Christians were properly supported for workplace ministry and evangelism.

"There are gloriously beautiful and effective parts of the body that have been marvellously equipped and strategically sent to every sphere of society in every nation of the world. They are the ninety-nine per cent of the body [of Christ] who are artists, technologists, athletes, lawyers, baristas and more," he said.

"We have for too long neglected to commission and train and bless and equip the ninety-nine per cent of the Church who are actually side by side with the people in the world we are trying to reach."

He continued, "Too many workplace Christians have been told implicitly or even explicitly 'we don't need you'. But we do.

"Can God really do His work through lawyers? Oh yes He can. Can God really do His work through domestic workers? Oh yes He can - and He is, through hundreds of Filipino believers in the Muslim world. And can God really do His work through a mere carpenter? Oh yes, I think we all know he can."

He cited a number of other challenges leading to "ineffectiveness and ugliness" in the body of Christ, including a sense of "isolation" and competition between ministries, "fighting" over financial resources, and highly publicised scandals involving Christians.

"The reputation of the bride of Christ in many places around the world is not good. Rather than people stumbling over the message of the Gospel as we see in Romans 9, too many are stumbling over the messengers," he said.

"Too many scandals of pride, power and impurity have robbed the Church and compromised our witness."

He called for repentance and humility over the Church's "flawed witness in the world" and "flawed mission to the world".

"This is not a moment of triumphalism but sober repentance and fresh resolve," he said.

Elsewhere in his address, Dr Oh paid tribute to Korean Christianity, noting that the country is home to some of the largest churches in the world and that it is the second biggest missionary-sending nation in the world.

Also addressing delegates during the opening ceremony was Rev Jaehoon Lee, senior pastor of Onnuri Church and chair of the Lausanne movement's Asia Co-Host Committee that helped to organise the congress.

He said that in an increasingly polarised world, the congress offered an important moment to think critically about some of the changes affecting the Church, like technology, the shift in the centre of Christianity to the Global South and East, and the challenges of raising up a new generation of young leaders.

"The world seems like it is getting more torn apart than ever before ... Can it be that God can deliver peace and healing through our prayers? Could it be that God can bring about hope and transformation through our partnerships?" he said.

The city of Incheon is significant to the spread of Christianity in Korea as the first foreign missionaries to the country arrived at its port in the 19th century to spread the Gospel.

Congress delegates were welcomed to Korea by the Mayor of Incheon, who paid tribute to the Lausanne Movement's "50-year legacy of world evangelisation".

Underpinning the congress are two documents, The Seoul Statement and The State of the Great Commission report, both published to coincide with the gathering.

The Seoul Statement is the work of the Lausanne Theological Working Group and draws on feedback from regional gatherings over the last 18 months.

Co-author Dr David Bennett called the document an "exciting milestone" that will build on previous Lausanne statements, notably the 1974 Lausanne Covenant, the 1989 Manila Manifesto, and the 2010 Cape Town Commitment.

The Seoul Statement identifies seven key areas that the global Church must collaborate on in order to fulfil the Great Commission: the Gospel, the Bible, the Church, the human person, discipleship, technology, and the 'family of nations', which focuses on people living in areas of conflict.

It rejoices in what God has already done through the Church to proclaim the good news of Jesus Christ, but says that the task of evangelisation "remains urgent as billions remain outside the reach of the message of God's love and grace in Christ".

"Moreover, in the face of this expansive growth, the church in many parts of the world has struggled to effectively nurture the faith and discipleship of millions of first-generation Christians," it reads.

The statement expresses "regret" that "during the last 50 years of evangelistic harvest, the global church has not adequately provided the teaching necessary to help new believers develop a truly biblical worldview".

"The church has often failed to nurture new believers to obey Christ's call to radical discipleship at home, at school, in the church, in our neighbourhoods, and in the marketplace," it reads.

"It has also struggled to equip its leaders to respond to trending social values and to distortions of the gospel, which have threatened to erode the sincere faith of Christians and to destroy the unity and fellowship of the church of the Lord Jesus."

The statement expresses alarm at the "rise of false teachings and pseudo-Christian lifestyles", both of which it says are "leading numerous believers away from the essential values of the gospel".

The statement calls Christians to renew their commitment to the centrality of the Gospel and the faithful reading of Scripture.

"Only in this way can we meet the specific challenges that now face the global church as we seek to bear faithful witness to our crucified and risen Lord — from everywhere, to everywhere, for the sake of generations to come," it says.

Dr Bennett said the document was both "strategic" and "action-oriented", and would address key theological "gaps" identified as necessary for strengthening global mission today.

"What do we need to do together? ... Are there areas of the fulness of God's desire for the nations [and] His desire for His Church where we have not listened carefully enough or where our changing world is raising new questions that were not answered fully enough in our three foundational documents?" he said.

The State of the Great Commission report considers 10 key questions that the global Church must consider as it looks ahead to the year 2050.

These include questions around the impact of artificial intelligence, changing societal attitudes towards gender and sexuality, the world's aging population, radical politics, Islam and secularism, and the growth of Christianity across the Majority World.

"Sub-Saharan Africa's youthful Christian population ensures the region's centrality to global Christian growth for decades to come," the report says.

"Christianity will increasingly be a religion of the aged in Europe and North America," it reads, adding that "mission is now from every continent to every continent".

"With the exception of Europe, every region in the world both sends and receives more missionaries than fifty years ago. Mission is increasingly decoupled from its Western colonial legacy, with more missionaries coming from countries that lack Christian majorities."

The report further notes that "with the exception of Africa, all regions will witness an increase in the proportion of the population that is unevangelized in the coming decades".

"This is a stark reversal of a century of growing gospel access around the world," it states.

During Lausanne 4, group sessions will be held to discuss 25 of the most pressing issues raised by the report.

The congress is being held in close partnership with hundreds of Korean churches. Some 4,000 Christians across the country have committed to praying for its success.