Jay ,  When we read e.g. the Acts we see a community of faith having to deal with three "sins" :
Apostasy , Adultery and Murder .  All committed by some of their own .  How could this be , they asked .  Is not the Spirit strong enough ?  Jesus salvific act not quite up to snuff ?
Experience teaches us that everybody is not yet confirmed in grace .  
Our darkness , weakness and propensity to do wrong still exists .  In other words it can be phrased that the false self has not yet been wholly healed .  The true self is being healed but we are not living from our true self all the time .   Nor are we our true selves yet !  This has very little to do with catechesis , knowledge etc . 
We struggle to dispose ourselves to opening to the work that only God can and wants to do :  make us whole .