The fundamental difference between the Reform and Orthodox view on Judaism is its very definition. To the Reform, being Jewish is a sense of identity and history, and nationhood. To the Orthodox, being Jewish is being a part of a religion, in addition to a nation. The Rambam (Maimonides) speaks of 13 principles of belief that one must have in order to be Jewish. There is an important place for people who are not observant in the Jewish nation. And we must make those individuals close to the Jewish People. However, we cannot allow them to distort Judaism as a religion. Religion is not democratic. The Truth is not defined by the people. People are not inclined to care about what is true or not. (See the multitude of psychological studies that prove this) People are inclined to believe in what is easy or good for them. We must accept non-observent individuals into the People of Israel, but never give even the smallest amount of acceptance to their religious practices or beliefs (so long as they are directly incompatible with the Torah-Halachic Jewish Tradition).
Hungary's Orban: Refugees threaten Europe's Christian roots (Reuters)
from the article: Prominent Orthodox rabbi calls on Israel to recognize Reform Judaism