The term missiology is a compound of Latin missio - "a sending forth," i.e. with a message; and Greek logos - "study, word, discourse." In Christian circles where the word originated, the message in question is the Gospel of Jesus Christ, and the goal of the sending forth is the expansion of the Christian faith. However, in recent years the term "missiology" has been applied to the study of the expansion of other religions, and phrases such as "Islamic missiology" and "Buddhist missiology" are heard with increasing frequency. So, in discussing missiology in the twenty-first century, it is necessary to specify which religion's mission is in view -- in the case of this article, Christianity.
Definition and elements
Christian missiology may be defined succinctly as "the science and study of the ways and means of the extension of the Christian faith." Examples of more complete definitions might be those of . . .
The process of the extension of the Christian faith includes at least these three major stages: 1) gaining converts or adherents in a location and/or among a people where the the Christian faith was previously unknown (or the community of Christians was extremely small); 2) instructing these new converts in the tenets (creeds, doctrines) and practices (sacraments, liturgies, lifestyle) of Christianity; 3) establishing a Christian infrastructure (local congregations, parishes, districts, jurisdictions, etc.) and institutions (schools, seminaries); and 4) developing these to the point where they are able to function adequately in relative independent from outside direction and assistance.
Missiology is of necessity an eclectic discipline, drawing for its principles on such diverse fields as biblical and systematic theology, cultural anthropology, psychology, sociology, history, geography, etc., and indeed any field which may inform the task of spreading the Christian faith to new places and peoples.