Christians and Islams are brothers is it true

It's the animosity between Christians and Moslems that get very much publicity and hype, historically speaking, culturally speaking. We are more than brothers I believe. We belong to one humanity. We belong to ONE and SUPREME God up there present in all of us more than we are in ourselves. I know there's been a history of suspicion between us, but as we grow older and wiser, as generations after generations ponder on the myopic-ness of our fathers in treating one another, I think we shall come into a time when we would consider what distinguishes us as something that must not separate us. I think, being Christians or Moslems are a diversity we should all celebrate, and not feel like going to war about. I am of the firm belief that Christians and Moslems, and Jewish for that matter, belong to ONE HUMANITY which calls for unity, respect, freedom and well-being.

I'm not sure but I've heard that there was a feud between Isaac and Ishmael. That muslims believe that Ishmael was the heir of Abraham and we christians believe that Isaac is the rightful heir. Not quite sure though.

No. If you say that Isaac and Ismael are brothers one may say that Jews and Arabs are brothers, but that does not lead us to saying that Christians and Muslims are brothers. There are Jewish Christians and Arab Christians though!