Which organization divided Palestine into the two countries of Palestine and Israel after World War 2?

Answer 1

The answer you are looking for is the United Nations.

However, the phrasing of the question misconstrues the authority of the United Nations General Assembly Resolution 181. Most people incorrectly believe that the UN Resolution "created" a Jewish State (Israel) and an Arab State (Palestine) on the map. This is not the case. What the UN Resolution does provide for is the permission for the different ethno-religious groups in Mandatory Palestine to declare a state. In the case of most mandates, the understanding was that the mandate would eventually become independent as one new state, like Iraq or Syria had. The case of Palestine was therefore unique and needed the permission to deviate from the traditional path of independence. Because of there being two states, provisional borders had to be provided, which is why a map was used, but those borders would only come into play if both sides decided to remain at peace.

The Jews acted on the permission granted to them by UN Resolution 181 by declaring independence on May 14, 1948 (nearly six months after the Resolution was passed) and therefore creating the State of Israel. The Arabs only declared the State of Palestine in 1988 in exile.