That is the point most non-Christians miss. Jesus knows that everyone is a sinner and we all fall short of the grace of God. Our best works are but filthy rags to him. That's why Jesus died on the cross to wipe away our sins.
When the spirit enters your body, you sin less but are still not perfect, not one of us. Just a lustful thought is a sin and is no lesser or greater a sin than killing a person.
We Christians are to try to be more like Jesus, not be exactly like him. If this was the standard to be perfect like he was, we would all burn in hell.
In the old days when a Christian sinned, he had to atone for the sin with a sacrifice. Jesus made this unnecessary with the new covenant.