[1] Renner and Peter Hartwig, both German Lutherans, were the first CMS missionaries in Africa, recruited to a mission in Freetown, Sierra Leone in 1804.
Both Hartwig’s and Renner’s letters home highlighted challenges presented in Sierra Leone, like that of food scarcity and frequent sickness.
There, Renner diligently worked to find Africans to convert, although between natural and physical challenges he was unable to fulfill this duty.
[citation needed] Once stationed at Bashia, Renner was refocused by religion and worked with parishioners, on a much larger scale than other German speaking CMS members that sought out new converts.
[3] Renner arriving in the Bashia settlement in Rio Pongas created and carried out a plan with the following points: By this time Renner and other missionaries were prepared to diffuse their religion into the people and the Church Missionary Society began to direct its attention to establishing institutions under the protection of the British Government.
Renner continued teaching in the Bashia settlement until he returned to Freetown in 1814 where he was put temporarily in charge of the Christian Institution leaving Elizabeth as the leader of the misssion.
The mission also experienced increasing numbers of conflicts and acts of arson attributed to the illegal slave traders and later identified to be caused by Jellorum Harrison who was paid by John Ormond.
[3] In 1818, the Renners moved to Leopold, a growing community of individuals who were rescued from illegal slave ships and returned to the Freetown area.