I dont understand what causes such division in the world whether it is in religions like Judaism or Christianity, or something like politics. Why is there so much divisions?

Shalom, Thank you for your question. Division in and of themselves are not negative. It is wonderful that each nation and group adds their special talents and character to the world. After all, what type of world would it be if we were all the same? Because of this, Hashem created the world in such a way that each nation can bring out a special force and flavor into the world. That’s why there are, according to our tradition, 70 nations. Even the tensions created because of these differences is not an intrinsically bad thing. These tensions help each nation strengthen their own character. Because of the forces acting against them, they must work harder to fully express themselves and this is a good thing. Each nation and grouping is pushed to an even greater expression of their special nature. And even when these tensions bring about open war between the nations, this is also sometimes a good thing, in the long-view. It helps root out the negative sides of each nation. The evil is reduced, and the good strengthened. (Of course, in the process there is much suffering – but the overall benefit is still great), None the less, you are correct that the ultimate goal is one of total unity and peace. A world where nations can each live expressing their particular part of the total good. However, the pathway to such a world is pathed with tensions and wars. May we be blessed with Shalom.