He mainly focuses on religious ethics, particularly in relation to the Islamic and Christian traditions.
Kelsay's 1993 book, Islam And War: A Study in Comparative Ethics, discussed the Islamic concept of jihad as compared with the Christian concept of just war.
[1] His 2007 book, Arguing the Just War in Islam, was praised by The New York Times for helping to bring greater understanding of Islamic views of war and peace to the non-Islamic world.
[2][3] In 2007, Kelsay visited Oman and urged students there to challenge fellow Muslims who used the concept of jihad to justify acts of violence.
[4] He has assumed the editorship of the interdisciplinary journal Sounding, which has moved to Florida after 25 years at the University of Tennessee.