Means and Numbers
Often touted as the "father" of the Protestant missionary movement, William Carey's "Enquiry" was one of the first volumes to defend the cause of Christian missions, make estimates as to the size of the non-Christian world, and develop strategies for undertaking missionary work.
Anglo-American missiologists like Rufus Anderson and Henry Venn supported efforts that built self-governing, self-sustaining, and self-propagating Churches. Thus, missions had a set endpoint, after which resources could be directed to a new site. The first African Anglican bishop, Samuel Adjayi Crowther both embodied and enacted that tradition in his career.
Civilization, Progress, and Development
Alexander Duff firmly believed that Christianity and "Civilization" went hand in hand. He encouraged educational missions and the spread of the English language and western culture.
German missiologist Gustav Warneck rejected the connection between Christian mission and Western civilization. Instead, he believed that missionaries ought to Christianize culture from within. This requires the use of indigenous languages, music, and other cultural forms.
"Women's Work for Women"
Helen Barrett Montgomery was a proponent of global women's cooperative work. She travelled widely, supporting the education and training of women and girls. As missionaries, women had unique access to women's spaces that outside men could not enter.
Heavy Hand of Western Paternalism
Roland Allen critiqued paternalistic attitudes of western missionaries. Rather than missionaries guiding the growth of new churches, Allen suggested they should cede power to local leaders and trust in the Holy Spirit's guidance.
Johannes Hoekendijk was something of a radical. He thought that rather than focusing on institutional questions, the Church should exist to reintroduce God's peace into a broken world.
While many mainline protestants became increasingly uncomfortable with the implications of conversion, the evangelical movement expanded its evangelistic missionary activity. Donald McGavran was a leader in this school of thought.