1f056552__Unequally_Yoked_to_the_World____in__the_world__not_yoked_
[Example] Focus [“of” the world (yoked)] Focusing on something of this world that is either unGodly or pulls you away from God you could be unequally yoked to a sport, a leisure activity or a business that requires you neglect God in order to achieve success in it. [“in” the world (not yoked)] 
You could be focused on something of this world such as sports or education without letting it compromise your Christian walk.
Brent Riggs - Designer, Author, Business Man - Question: What Does It Mean to Be Unequally Yoked to the World?
“in” the world (not yoked)