Before the seventh century Christianity predominated from India through the middle East to Western North Africa. Through conquest and conversion most of these areas, excluding, Armenia became dominated by Muslim overlords. Constantinople itself held out for some time but it too became overrun.
The Sharia (Muslim law based upon the Qur'an) considers an area either under Islam or under war. Dhimmitude, a word coined by Bat Ye'or, is used to describe the situation of the so-called "protected people" who may retain their religion but must pay exhorbitant taxes. Dhimmis (Christians and Jews i.e., people of the book) are not immediately enslaved. But if they do not convert they are triple tax viz a viz their Muslim neighbors. Should they try to escape they are brought back and put into slavery. This can be seen most clearly in Sudan today.
Part of the reason some conversions were so easy is because of the Byzantine tendency to impose its will upon the various groups of the empire. They cared little for the welfare of these people. Many easily converted because they saw a better way. Those who did not or have not converted face terrible hardships.
So, is there anything in addition to prayers and money we can do to help? Would missionaries be helpful?
BTW Why don't we have missionaries in the BC Church?