What must I do?

That's a subtle, yet profound contrast. I've never seen that before.
I recently wrote a post concerning the fact that false converts always speak in terms of getting to heaven and don't speak of the preciousness of Christ or of sorrow over their sin. This is the perfect illustration of that!
Thanks!

In the verse below, please note that the branches cast out of our vine Jesus are not withered, meaning they are 'alive' and interested in getting personal benefits from the religious life.
Joh 15:6 If a man abide not in me, he is cast forth as a branch, and is withered

Dear Overseas,

Perhaps you may have sleightly misunderstood the context for which I was speaking. The Scripture shows that we need to make a differentiation between a regenerate and an unregenerate person. The verses above in my post are all directed to unbelievers, or those who are spiritually dead and desperately need Christ. The goal of the gospel is to help people see their own spiritual bankruptcy and utter hopelessness of looking to their own resources for salvation and their need of a Savior.

Unebelievers do not merely need to add Jesus to their life (how do I get eternal life). They need, by the grace of God, to die to their old life. All hope in self is lost. Nothing in it must stand but be torn down completely. No hope in anything save for Christ and his mercy alone. Only those who God reveals this truth are given the grace of faith.

Your example above in John 15 is Jesus speaking to disciples, who already understand this, and encouraging them to persevere ... but they already recognize their utter need for Jesus. Note in John 15:16 Jesus assures them that he will preserve them to the end: "You did not choose me, but I chose you and appointed you that you should go and bear fruit and that your fruit should abide."