What religion was most of the Middle East and Northern Africa before Islam?

Christianity was the dominant religion in both regions, simply because most of the non-Persian Middle East/North Africa had been ruled by the Christian Eastern Roman Empire for more than three centuries by the 630s. In all likelihood, there were probably many pagans around in the countryside or in less accessible regions, but they lived in a Christian empire and we don't hear much about them from Christian writers (who are our main sources for this period), so we can't be sure about how many there were. We do know that some regions had significant religious minorities living there though, such as Palestine, which had a substantial population of Jews and Samaritans. Arabia is another example, as it lay outside the boundaries of the empire and was home to pagans, Jews, Christians and Zoroastrians. Unfortunately, none of this can be backed up by population statistics and the image of a Christian Middle East/North Africa is definitely too simplistic, but as political power lay in the hands of Christian emperors, I think it is justifiable to say that it was largely Christian (though Christianity itself was also divided into many, many factions in this period).