There are three 'western' religions that are based on the same idea. The are all based on the idea of doing good in this life on Earth to get to a better one with Him. They have the same major prophets and the same holy land. This would make sense if they originated far away from each other and had different prophets/saints. Are people so stuck up that they cannot even share a religion? Even within religions there is dissent and new sections are formed.

The reason behind these separations has to be rooted in the fundamentals of human nature. Why else would three different religions with the same ideals form around the same time, with similar prophets, in the same area of the world. This is the same idea why people who have the same ideas tend to still disagree and argue. Everyone has an idea on what should happen, these ideas are so holistic that they usually include only two or so umbrella ideas that hold essentially the two viewpoints. Underneath these two umbrellas however you find people who think that to find world peace, we need to ban all guns and then those who wish it but don't know how it could happen. These two subgroups, even though they want the same end result, will argue and disagree. This forms different groups with barely any differences in their overall views but only in their fundamentals. Whether or not these divides are silly, they happen all the time. Two people can have the same overall view but differ in their ideas on how something should be executed. This can ruin a relationship. I think this makes these divides rather silly.