why was the religious legislation of feudal governments a succes
There are several sites in here that should help you:
http://www.google.com/search?q=religious+legislation+medieval&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
Your question is very broad, though, and you may need to re-search using different terms.
"feudal governments" where? In Europe? In Japan? Where?
"religious legislation" by whom? the Catholic Church? the Japanese emperor or any of his priests? about what? regulating whom or what?
If you need help learning how to search, including how to choose good search terms, go here and scroll down to the links under HOW TO SEARCH THE INTERNET:
http://hanlib.sou.edu/searchtools/
=)