By the Spirit or by Natural Inclinations

“You, however, live not by your natural inclinations, but by the Spirit, since the Spirit of God has made a home in you. Indeed, anyone who does not have the Spirit of Christ does not belong to him. But when Christ is in you, the body is dead because of sin but the spirit is alive because you have been justified; and if the Spirit of him who raised Jesus from the dead has made his home in you, then he who raised Christ Jesus from the dead will give life to your own mortal bodies through his Spirit living in you.
So then, my brothers, we have no obligation to human nature to be dominated by it. If you do live in that way, you are doomed to die; but if by the Spirit you put to death the habits originating in the body, you shall live.” (Romans 8: 9 – 13)
To live by the Spirit is the opposite of living by the flesh or by human inclinations. The flesh is served by 5 senses: eye, ear, nose, tongue and touch. Living by the Spirit means walking by faith and not by the evidence of the 5 senses. Sometime ago, I watched on 20/20 the case of a Californian man who spent 10 years in jail based on the visual evidence of a rape victim. DNA evidence later exonerated him. There are many such cases of wrongful imprisonment based on physical evidence. The certainty of the jury in passing sentence never suggested any shade of doubt that they might be wrong. It reminds me of the trial and imprisonment of Joseph in Egypt.
To live by the Spirit is to live by faith. The above scripture says with certitude that the Spirit of God has made his home in us. Praise God.