The greatest threat to the Church today is presented by Islam.
The largest block of unreached people (over 1 billion) are Muslims.
In Africa, over 40% of the population (260 million people) are Muslims.
Through the ages Islam has been the largest and most vicious opponent and persecutor of Christians. By the tenth century the Muslim armies had annihilated half of all the Christians in the world of that time. Today the Islamic Jihad against Christians continues and the sharpest confrontations between Christianity and Islam in the world are in Africa.