Jeremiah 12:14-17 is an obscure passage in the bible. However, it does a really good job of explaining the Complex dynamic relationship between God, Israelites ( also reflective in today's world as Christians ) and Gentiles ( NonChristians ).
Jeremiah 12:16(a) is particularly interesting because it suggests the possibility of NonChristians finding salvation in God by learning the ways of Christians.
Conversely, Jeremiah 12:16(b) indicates that Christians fell into sin by learning the ways of NonChristians.
Jeremiah 12:16 reflects a "pendulum"-like nature of the dynamic relationship between Christaians & NonChristians-- it could go either way.
Incidentally, one should mention that Jeremiah 12:16 evokes the following verses of warning :
Furthermore, Jeremiah 12:14-17 also evokes & gives credibility to the bible verses, John 17:11 & John 17:14-16. The reason being is that God views understandably as a premise that Christians will be "in the world" with NonChristians but are warned to be "Not of the world"