The United Nations provides no benefit to the United States. Even more recently, it shows that the beliefs of the United Nations differ significantly from the United States. If you have not heard, the United Nations wants America to rid of the 1st Amendment in order to combat racism. It has gone to show that the UN doesn't have any good intentions for the United States. With the United States being an independent country (compared to others of the UN) has no benefit of staying. However, if the United States left, the UN's funding would be cut significantly, and with the most influential country in the world leaving, other powers like china, may follow suit and if the 3 major super powers, US, Russia, and China, it would dismantle the UN internally,
Yes, the United States should withdrawal from the United Nations, because the United Nations has no standards. The United States also funds a large portion of the operations of the United Nations, and they don't get much to show for it. The United States would be better off pursuing other treaties and peace accords, rather than the United Nations.
The United States and United Nations do not have ideological discrepancies in that both entities want peace and democracy. The major break from the UN came in 2003 when the United States invaded Iraq without the permission of the Security Council since Iraq wasn't threatening anyone except its own people. The U.N. and U.S. have similar missions, even if some countries in the United Nations disagree.