Because people who still sin - are NOT of God.
1st John 3: 8 "He that committeth sin IS OF THE DEVIL; for the devil sinneth from the beginning. For this purpose the Son of God was manifested, that he might destroy the works of the devil."
If you still sin - then you're NOT a Christian.
You're just a sinner - CLAIMING to be a Christian.
That doesn't make you one.
Every time you sin - you prove who you really serve.
Jesus said so.
John 8: 34 "Jesus answered them, Verily, verily, I say unto you, Whosoever committeth sin IS THE SERVANT OF SIN."
Jesus doesn't lie - Does He?
NO - He does not.
You're just lying to yourself.
REAL BELIEVERS CANNOT SIN.
1st John 3: 9 "Whosoever is born of God doth NOT commit sin; for his seed remaineth in him: and he CANNOT sin, because he is born of God."
If you still sin - it's because you're NOT Reborn.
Jesus said so...
Matthew 7: 18 "A good tree CANNOT bring forth evil fruit, neither can a corrupt tree bring forth good fruit."
Jesus doesn't lie.
Abd every time you sin - you PROVE which tree you REALLY are...
And you either want REAL answers....
Or - you choose to serve sin over and over and over again for the rest of your life like you have been your ENTIRE life.
Very simple.
Either way, every time you sin, you PROVE who you serve.
Romans 6: 16 "Know ye not, that to whom ye yield yourselves SERVANTS to obey, his servants YE ARE to whom ye obey; whether of sin unto death, or of obedience unto righteousness?"
You CANNOT serve two masters.
Stop lying to yourself.
If you want the answers - ask.
Or - Keep serving sin.
Make your choice. Either way you ARE choosing.
Take care.