In the lonk you givem Israel isn't listed by UNESCO under "Arab States" - for which I'd guess you'd be happy. Scroll down and you will find Israel listed under "Europe and North America". Which Europeans and North Americans might find puzzling. But UNESCO recognises Israel as a state. Israel is a member. Only states can be members.
Republican former Virginia Governor Jim Gilmore files paperwork to enter presidential race (AP)
from the article: Israel slams 'absurd' UNESCO decision on Jerusalem, West Bank holy sites