A zealot.
Religion is usually spread by one person impressing another person with their good character, kind heart, and inner glow.
Muhammad.
A missionary
A preacher or a missionary.OR if its in forceful ways its a terrorist or a crusader.But really anybody who is religious and talks about it works to spread his religion
It was Jesus Christ via the missionary work of the apostles. Christianity was the monotheistic religion which spread in the Roman Empire.
Missionaries are the people who help spread a religion.
If we take time as a measure of the spread of religion,then since its establishment ,Islam is the religion which spread or still spreading rapidly in Asia followed by Christianity.
Islam spread from Arabia.
It spread by Christian missionaries looking for a new place to spread their religion
That person would be called a missionary. The work would be called missions.
Islam was the religion that spread from the Arabian Peninsula to Africa.
Migration is cause of spread of religion. As people travel they bring along their religion, and the constitution does not prevent them.