In
Acts 15, James, and God, made it clear that what the 'gentiles' were required to live by what the Jews consider the Noahide laws.
Abstain from:
things contaminated by ('consecrated to') idols
from fornication
from what is strangled
from blood
The Jews, as a religion, considered those that did those things (those that obeyed those commands, that is), but did not get circumcised, as "God Fearers"... that's what Cornelius was.
The Jews required this of any proselytite they won from among the gentiles (who did not get circumcised to identify themselves with the nation of Israel), so it makes total sense that this is what they expected of the new gentile converts to this extension of Judaism, which was faith in the Messiah... As a matter of fact, the circumcision argument was what brought this whole debate on to begin with in
Acts 15.