Jeremiah 3:10
And yet for all this her treacherous sister Judah hath not turned unto me with her whole heart, but feignedly, saith the LORD. And yet for all this her treacherous sister Judah hath not turned unto me with her whole heart, but feignedly, saith the LORD.
Judah is called treacherous because she persisted in unfaithfulness even after seeing Israel's unfaithfulness and its consequences. Her turning to God was not with the whole heart but was insincere and pretended, an apparent repentance that was only feigned rather than wholehearted return. The same description applies to people who profess to belong to God while remaining blind to their own backsliding.