The Oslo agreements of 1993 established a Palestinian Council to negotiate with Israel the permanent status of the West Bank and Gaza. Article V of the agreements states:

• a) Permanent status negotiations will commence... between the Government of Israel and the Palestinian people representatives.
• b) It is understood that these negotiations shall cover remaining issues, including: Jerusalem, refugees, settlements, security arrangements, borders, relations and cooperation with other neighbors, and other issues of common interest.

The aim of the negotiations, as written in Article I of the Oslo agreements, is to achieve a permanent settlement based on Security Council Resolutions  242 (1967) and 338 (1973). Neither of these Security Council Resolutions calls for the creation of a Palestinian State in the West Bank, as witnessed by the address delivered by President Ronald Reagan on September 1, 1982:

...as we look to the future of the West Bank and Gaza, it is clear to me that peace cannot be achieved by the formation of an independent Palestinian state in those territories... so the United States will not support the establishment of an independent Palestinian state in the West Bank and Gaza.

If Security Council Resolutions 242 and 338 called for the creation of a Palestinian State in the West Bank, then Reagan would not explicitly veer from such declaration. Thus these resolutions do not call for the creation of a Palestinian State in the West Bank.  

In the Oslo agreements, permanent status is to be achieved only through Israeli-PA negotiations.

The members of UNESCO are nation states. A nation state has borders, a capital, engages in international commitments, controls its air space and borders including immigration, etc. When the PA applies for membership as a nation state in UNESCO, then the PA alone will decide these above matters; for instance, the most basic matter of what are its borders and what is the nature of its capital Jerusalem, without negotiations with Israel. This is a direct rejection of the Oslo agreements.

There have been many violations of the Oslo agreements; e.g. incitement, Hamas, etc., which while demonstrating an antagonistic attitude towards Israel, do not present immediate danger to Israel. To claim to be a nation state means to control borders and airspace. Ground-to-ground and ground-to-air missiles will be helicoptered into the West Bank directly from Syria. Missiles that are fired today from Gaza into the southern Israeli cities, will be fired from the West Bank into the Israeli heart land.

UNESCO, not a signing party to the Oslo agreements, can reject these agreements but cannot void them. The PLO (PA) being a signing party to the Oslo agreements by rejecting them voids them.

When two parties agree to a dual and binding commitment and one party voids the commitment, then the commitment is voided also to the second party. Thus the acceptance of the PA into UNESCO with full membership voids the Oslo agreements, and releases Israel from any obligations to the Oslo agreements.

Equivalently, on the most fundamental issue of the Oslo agreements, reaching permanent status only through negotiations, the PA by applying for UNESCO membership (granted only to a nation state), interprets the Oslo agreements to be non-binding. An Oslo agreement non-binding to the PA, is non-binding also to Israel, and in essence is non existent.