John 15:16 talks about us bearing fruit that endures. In various translations it uses the words: abides, lasts and remains. In a sense, this is an oxymoron as fruit by its very nature decays and has a sell by date. Fruit has to be eaten fresh.
Yet here Jesus is talking about fruit that endures or remains. In this context, Jesus was referring to himself as being the vine and us as the branches. The branches draw their life from the vine as the sustenance is drawn up through the roots. Apart from the vine, the branches die and cannot yield fruit but, as part of the vine, they can yield an abundance of fruit.
The fruit can only be the same as the tree. Branches of an apple tree can only yield apples. So, when we are connected to the eternal God, we can yield eternal fruit. He is the one that sustains us; our nourishment is drawn from him. Therefore, if we draw from an eternal source, it is easy to understand how we can yield an eternal fruit.
Provided we stay embedded in the eternal God, in the true vine, then we will produce eternal fruit. Fruit that endures, fruit that remains. The branches of a tree do not have to struggle or strain to produce fruit. They just have to let the life from the tree flow through them and the fruit is produced automatically.
Let us make sure we remain connected to Jesus, that there are no obstacles for the flow of his life through us. Then will we know fruitfulness.