Urbanization has played a very significant role, because families have had to be separated. Men leave their families for up to a year. While they're away, the temptation is very, very great. Another is the displacement of people because of war. With that comes the complex nature of troop movements and their actions in camps.
Some armies are notorious for promiscuity and rape.
The health issue is another one. Without the opportunity for good healthcare or treatment of other sexually transmitted disease, the risk for contacting HIV jumps about eight times. The combination of all those factors has just caused this continent to be exploding with this virus. That's a hard question to answer, because it does hinge on the definition of Christianity and a commitment that is more than surface. That's a tragic part of much of the church in Africa.