The Third Sin Problem is not universal … only believers have it.
Believers still sin and believers still have messed up lives.
Actually, only believers qualify to have this problem
because only believers can experience the Solution to Sin Problem #3.
Two visible evidences of this 3rd Sin Problem are:
It is surprising that God did not fix this problem in the believer
when the believer believed into Christ crucified and was changed.
Yet, when He solves the two universal Sin problems in them, God so changes (transforms) believers
that believers are able to have a part in His solution to this Sin Problem, by confessing their sin (I John 1:7,9), and by choosing not to sin.
Since unbelievers are not changed as believers are, they unable to deal effectively with their sins.