Chidi Anselm Odinkalu writing in Premium Times:
Irrespective of how it is acquired, the belief is popular among many African communities that “power comes from God”. Around the continent, atheism is not a natural vote winner and when, at the end of the contest, they get installed into powerful positions, many politicians organise “prayers and thanksgiving”.More here
Since God gives power, it is only sensible to look to Him to keep it. As such, many African presidents and their retinues employ the most able among the wondrous men who sell mysticism and magic for money and power. A powerful politician in mortal peril of loss of power through ill health is, naturally therefore, a boon to merchants of god.