Ontology is the study of being -- "We are, therefore, we be" (or something tricky like that). We know that we exist. Ontology is the study of the nature of being or existence. We know that human beings are finite beings. We once did not exist, now we do. As we compare Christianity with Islam, we will come to the crucial issue of the nature of Muhammad compared to the nature of Jesus.

Muhammad and Jesus are ontologically different. The difference is so large that, without the difference, we have no Christianity and we have no Gospel. Islam makes no claims that Muhammad was any different than you or me, except that he was a prophet of Allah. In other words, Muhammad fits in with all the rest of humanity who are finite creatures. As we compare Muhammad to Jesus we find that there is no comparison -- ontologically speaking.