Keith taught for 5 years in the Solomon Islands at Su'u Secondary School, before returning to Australia and theological studies at Whitley College. He went on to Doctoral studies in New Testament with Rev Dr Athol Gill, and then taught for three years at the Baptist Theological Seminary, Rüschlikon, in Switzerland, before coming back to Whitley in 1994. He is the author of The Prophecy on the Mount (Mk 13) (1998) and co-editor of Resurrection and Responsibility (2009). Keith was the Chair of the Academic Board of the Melbourne College of Divinity (2006–09) and is now Deputy Chair of the Coursework Studies Committee.