Why are there fewer christians in northern africa

The reason why there are fewer christians in northern Africa is because the culture in Africa is different from christianity.

North Africa is dominantly Islamic region. Islam in general is not very tolerable towards other religions and over time there has been forced assimilation of the Christian population, and by some extreme groups even making genocide (that was well hidden from the public eye of the world). The dominant Christian population of Northern Africa were the Barbers, but because of the aforementioned processes, their number is decreasing with each year.