Yes the quote in bold is accurate and from the bible.
It mean just what it says.
7 Little children, let no one deceive you. He who practices righteousness is righteous, just as He is righteous. 8 He who sins is of the devil, for the devil has sinned from the beginning. For this purpose the Son of God was manifested, that He might destroy the works of the devil.
1 John 3:7-8
This is a contrast of those who practice righteousness,
A person who practices righteousness, is righteous.
A person who practices sin, is of the devil.
He who sins is of the devil.
The devil himself sinned, as sin affected him, just as it affects humans.
The person who practices righteousness has the same flesh body as the person who practices sin.
This scripture does not say that the devil dwells in the flesh.
This scripture does not say sin is of the devil.
This scripture states that the person who sins is of the devil.
Read it for yourself... He who sins is of the devil.
Not everyone has been given a messenger of Satan to buffet them, this was unique to Paul, because of the abundance of his revelations.
JLB