What is the relation between Christianity and islam?
Islam and Christianity are both monotheistic religions. However the Christian religion does not identify Muhammad(s) as the last prophet or even a prophet. Islam recognizes Muhammad(s) as the last prophet and recognizes all the other God prophets that the bible recognizes, including Adam, Noah, Abraham, Isac, Moses, David, etc.
In addition to the above:The two religions, Christianity and Islam, have in common all social values and principles of life. Both religions call for good deeds such as honesty, helping the poor, taking care of old people, to be nice and sympathetic with women and children, not spoiling the environment, to be kind with animals, not to kill without authority, not to steal, not to cheat, not to terrify the innocents, ... etc. These common social objectives of both religions should be acknowledged as important key to bring world societies to peace, love, and justice.
In addition, both religions share same faiths that believe in God, Day of Judgment, Paradise&Hell, Angels, and prophets (although Christians not believing in all of them)