You are wrong newseed, Islam does not *tolerate* fighting and war, it *orders* fighting and war when it is necessary, and tells how to do it.
You keep saying core of Christianity is peaceful. What would that mean if it is not demonstrated on the surface? Again, Christianity does not have means to enforce its commandments. What would one expect from an individual if he believes he already booked his place in the heaven?
Islam on the other hand acknowledges realities, and teaches us that it is our belief and deeds combined that will take us to the heaven. And that gives a sense of responsibility in every instant of life, something which Christianity lacks.