I believe that Orthodox Jews views people as Jewish whether or not they actually practice their religion, as long as their mother was Jewish, so Orthodox view seculars as real Jews. But if someone converts to a different religion, the Orthodox o longer view that person as Jewish. So they believe that Reform Jews are practicing a different religion, and are therefore not really Jewish. There are so few Jews in the world, I do not understand why they are trying to drive a wedge between the two main factions that survive.
U.S. confirms ISIS computer expert killed in air strike (Reuters)
from the article: Why oppose my rights as a Reform Jew in Israel?