The president of the All Africa Conference of Churches strongly cautioned people to beware of churches that exploit people in the name of the Gospel.

Speaking at the Ecumenical Platform of the World Social Forum in Nairobi, Kenya, on Sunday, the Rev. Dr. Nyansako-ni-Nku urged mainline churches to “rescue” people who are being lured by controversial African Pentecostal churches, which he described as a "disease," AACC reported Monday.

Nyansako, who heads the fellowship of 169 churches and Christian councils spanning 39 African countries, criticized African Pentecostal preachers for promising prosperity to followers but getting richer themselves while the congregations get poorer.

All over Africa, there is a surge of "one disease called Pentecostalism," he said, according to AACC. Nyansako repeatedly noted the rapid growth of the Pentecostal church during his talk.

Overall, there is an estimated 400 million Christians in Africa.

Pentecostals today represent about 12 percent, or about 107 million, of Africa's population according to the World Christian Database. Charismatic members of non-Pentecostal denominations make up another 5 percent of the population, or about 40 million. The proportion of Pentecostals and Charismatics combined was less than 5 percent just over three decades ago.

AACC’s Nyansako attributed the growth of Pentecostal prosperity churches in Africa to their exploitation of ignorance, emotions and poor class of the vulnerable who are ostracized by society, according to the church group.

Mainline churches were urged by the reverend to counter the problem by reaching out to the vulnerable in their societies and strengthening its credibility by making sure it performs what it preaches.

As an example, Nyansako said the AACC became the first church organization in Africa to undergo a thorough social audit. He urged others to follow, explaining that the procedure gives the organization the moral authority to speak against corruption.

He said the church should not be passive but instead be actively involved in politics, condemning what is biblical unjust and applauding what is right. However, he warned against the clergy being involving in partisan politics and compromising their integrity.

Nyansako said the Church is the last hope for many Africans because politicians have failed them and now the people trust the Church more than the government.

"This means the Church must take its mandate very seriously as we are the mantle of the continent of Africa and if we let the continent down, it would be a disaster for everybody," he said, according to the report.

The World Social Forum is a massive conference focusing on economic justice but also on other global social problems such as HIV/AIDS and human rights. This is the first time the Forum has been completely held in Africa and has attracted some 46,000 participants.

Other Christian groups attending the conference include the World Council of Churches and the Lutheran World Federation.