The picture is of the vinedresser (i.e. the Father), getting rid of dead wood so that the living, fruit bearing branches may be sharply distinguished. This is a picture of apostate Christians who never genuinely believed and will be taken away in judgment; the transforming life of Christ has never pulsated within them.
God removes all things in the believer’s life that would hinder fruit bearing. I.e. He chastises to cut away sin and hindrances that would drain spiritual life just as the farmer removes anything on the branches that keep them from bearing maximum fruit.
Just as a peach tree which bears no fruit is cut down and burned, that is what is done with branches on this vine that do not produce at all. Just as a peach tree must be pruned to put out beautiful fruit, these branches here are pruned to make them grow better and stronger.
The best fruit comes from the new growth after the pruning. You see, God cuts away the dead part of the branch, so that the new growth will produce more fruit.
We workers for Jesus must not get self-satisfied and stagnant. We must be growing all the time in the Lord to be productive. Remember the best results are from new growth. You will never stand still with God. You will either be going forward or backward.
We are not dealing here with the loss of salvation, but with the bearing of fruit of true believers.