felix culpa
Concise Oxford English Dictionary © 2008 Oxford University Press:
felix culpa /ˌfiːlɪks ˈkʌlpə, ˌfeɪlɪks, ˈkʊlpɑː/
▶noun Christian Theology the sin of Adam viewed as fortunate, because it brought about the blessedness of the Redemption.
– origin L., lit. ‘happy fault’.
'felix culpa' also found in these Oxford entries:

