How are the roots of Christianity and Islam similar? How did the development of each influence the other?
They both share the same god, the god of Abraham. Think of it like the protestant churches splitting from the Catholic church and now we have lot’s of Christian churches. Well in the same way Christianity and Islam split from the Jewish religion following different prophets. Christianity had Jesus and Islam had Mohammad.
The two are very different religions and even dislike each other very much even though they share the same god.