There have being a wide misunderstanding about these two terms; sin and flesh popularly tagged as self
Quickly note this flesh isn’t necessarily a SIN.
So what is a sin and what is flesh??
SIN is the transgression or disobedience to the law of God. So when you disobey the God’s commandments you have sinned.
Also know that in the cause of your walk with God there will be some personal laws that governs your relationship with God, for example God might instruct you to eat once a day for five month, if you go against it then you have sinned.
ROM 5:18 “For as by man’s disobedience many were made sinners…”
FLESH is any manifestation or desire that is contrarily to the perfect will of God. For instance when you should being praying you decide to sleep you haven’t sinned but flesh has taken over or when you insist on what you want above what God wants, its flesh(self).
In the Book of Romans the bible clearly explains that “so then they that are in the flesh cannot please God” ROM 8:8
Also know that those who so much desire the things of the world above the things of God are enemies of God
James 4:4 “…whosoever therefore will be a friend of the world is the enemy of God.
That’s why its advisable to properly examine yourself each day to see where you must have fallen, what you so much desire, what you are exhibiting and make amends quickly to still be in a good relationship with God 2cor 13:5 “examine yourselves, whether ye be in the faith…”
Examine yourselves today, anything that doesn’t exhibit Jesus, make do away with it that God may be proud to call you a son or a daughter of the most High