Abandoning a work's righteousness way of thinking and doing life, and trusting in Christ's faithfulness (His finished work on the cross, resurrection, perfect obedience to the Father on our behalf, His righteousness, His perfection, His everything), our hearts open up to His transforming work by the power of the Spirit, where He births new desires in us to please Him (loving Him and others).
So when we trust in His faithfulness, we begin to function in / operate out of the realm of grace and Spirit. The fruit of the spirit is love...
But when we trust in our own works, we function in / operate out of the realm of flesh (sinful nature). The fruit of the flesh is sexual immorality, impurity...
So Paul isn't telling us to revert back to works, by giving us the list. You better stay away from this or else!! No, he's reminding the listener to embrace and live out of the right realm...the realm of the Spirit, because when we do, the Spirit begins to birth new things in us.
The Spirit gives us desires that are the opposite of what the sinful nature desires...so let's side with the Spirit, and learn to walk in step with Him.