Islam has had its effect on Africa, all right. In the north, the thriving agriculture, and flourishing civilization of migrants and Phoenician traders and Jews and christianized Berbers, the Other Shore of Mediterranean civilization, from where among others Tertullian and Augustine of Hippo came, was destroyed by the Arab Muslim invaders, with the consequences for North Africa that we can all see. It was only in the period of French rule in Algeria, from 1830 to 1962, that agriculture was revived (including that of the vineyards), that the desertification that Arab non-methods of cultivation brought everywhere they conquered was reversed, and where universities, museums, and other outward and visible signs of civilization were established and maintained. For that moment, Algeria again possessed something like civilization -- and now it has relapsed, as of course it could have been predicted that it would, into a scarcely endurable and violent place, where the only hope is to get, as those chanting crowds repeated when they came out to "greet" a visiting Jacques Chirac a year or two ago: "Visa, Visa!"
What about black Africa? If you wish to see the traditional Arab Muslim treatment of black Africans, look at the 2 million dead over the past 20 years of scarcely uninterrupted warfare and genocide in the southern Sudan. If you wish to see the traditional Arab Muslim treatment of black African Muslims, prompted by the Arab supremacist ideology that Islam carries within it, and that does not admit of non-Arabs being as "fully Muslim" as the Arabs, look at Darfur, through the lenses even of Nicholas Kristof.
If you seek other examples, look at the unceasing pressure of Muslims in northern Nigeria on the Christians of southern Nigeria. Read again the Ahiara Declaration of Col. Ojukwu, in 1969, the leader of the Biafran Nation. Advanced Christians, chiefly but not entirely Ibo, sought independence as a way of protecting themselves from the "Jihad" (Col. Ojukwu's carefully-chosen word) being waged against them.
If you seek other evidence for what Islam, what Arabs, have meant for black Africa, do take a moment to read Willis on the Arab slavers of Africa, and the Arab slave trade that began earlier, and ended later (where it ended at all) in black Africa. Do read Jan Hogedoorn's article "The Hideous Trade" about the Arab slave trade, which was far more ruthless and genocidal in its effects -- for the Arabs liked particularly to seize young boys, who were castrated on the spot, and if they survived the initial primitive surgery, were forced to endure a long trip overland through the bush to arrive either by land or by dhow in one of the Muslim slave entrepots, Cairo or Jeddah or Muscat, Damascus or Baghdad or Constantinople or Algiers, or even distant Smyrna. Hogedoorn offers a complicated economic analysis of why the castration was done on the spot, which caused so many, on their subsequent forced march, to die. He estimates that only 10% of those castrated survived the trip in coffle or caravan to be sold in the Arab and Muslim slave-markets.But it is for freedom Christ has set us free.
And while we are at it, let us remind ourselves that slavery was never really abolished, except in theory, in many Arab states. Tens of thousands of blacks still are enslaved in the Sudan, in Mali, in Mauritania -- and their masters are exclusively Muslim and Arab. Though slavery was officially abolished in Saudi Arabia, out of a desire to placate those pesky Infidels (before OPEC gave the Saudis the power to ignore them) in 1962, it continues still. This can be deduced from certain advertisements in the Saudi press (a kind of Saudi version of the Yankee Swap; a “young girl" will be traded for a "late-model American used car." What would a Yard Sale of cast-off slave girls look like?).
There never was a Muslim William Wilberforce. Slavery is in the Qur'an, and Muslim clerics in Saudi Arabia have expressly reasserted that slavery is right and just. They argue that it cannot be ended because it is part of the practice of Muhammad and His Companions, whose sayings, acts, and attitudes give Muslim believers the Sunna -- not merely a secondary source of Islamic doctrine, but one for many at least as important as the Qur'an.
Oh, one could go on all day about what Islam has done to Africa. But don't ask me. Ask a black, non-Muslim African -- one who has some direct experience, possibly by living in an Arab country, of what Islam is all about and what it has done to black Africa. You might find someone who remembers the slave-trade conducted from Zanzibar and Pemba, now part of Tanzania, where the Arab Muslims are again displaying their wonted master-race attitudes.
The Sudan was scarcely 10% Arab in 1900. Now it is at least 50%. How do you think this happened? Did the Dinka, did the Nuer, cease to have children? How did this demographic change take place? In West Africa, aside from the Sokoto Jihad, what caused Islam to expand at the expense of Christians? What caused a frightened Nigerian female journalist to suddenly leave her country a year or two ago, when during the Miss World brouhaha (Muslim protests, which caused the event to be moved) she mentioned Muhammad's appreciation for pulchritude, and received for her admittedly silly sally death threats in return?
Why did it take the French to finally end the slave trade in North Africa? And why was it -- see J. B. Kelly, Britain and the Persian Gulf, 1795-1880 -- that only the British, using naval power (and staying carefully away from the interior of Arabia) managed to suppress the slave trade in East Africa, because not a single Muslim Arab had the slightest moral qualms about it -- nor does today? If it was good enough for Muhammad, if it is in the Qur'an, well then who is to object to slavery?
There is much more one could write....