Sudan and the UN

That someone
In the 20th century could actually be executed for apostasy, and not by a bunch of ignorant villagers but by a state that is a member of the UN not only boggles my mind but makes me wonder why the UN doesn’t just kick Sudan out altogether.
This us the same country that has just sentenced the Christian mother to death for apostasy (but, so nicely, only after she has weaned her baby).
What is the conceivable point of having this so-called country in the UN?
http://www.iqri.org/en/articles/mahmud-muhammad-taha-muslim-reformer-who-dared-die-his-convictions

Religious freaks… You can’t live with 'em ('cause they might kill you). And you can’t live without 'em ('cause there is always going to be some).