Don't you think that the problem is not Islam or Christianity but how some people are selfish and reject others?
Absolutely. I would agree with you that most of the things that we nominally fight about in this world are really just covers for the fact that we like to find people who are "like us" and then form tribes. We get into those tribes and look for other tribes to hate. We can see this at every level of life. You get the fans of one team hating the fans of another. You get people from various Christian sects (or Muslim ones, for that matter) hating one another. You get different political parties' partisans hating one another. It's all connected to our desire to identify with "self" and to hate the "other."
That's a great analysis and question and a great answer above.
I would also agree with you there, and go on to mention that when you look at religious teachings, you often find they are tolerant, however, the problem often lies with certain people forming their own twisted interpretations.
Both Islam and Christianity advocate tolerance, unfortunately, not every follower of a religon or way of life actually properly follows it to the bone. Often times, cultural and political affairs also get in the way, and unfortunately, some use 'religion' to do bad things.
I think if people actually followed their teachings properly, there would be less hate and strife, yet people are often swayed to form you/me conflicts for a variety of reasons.