In the Fourth Gospel, Jesus addresses the essential problems of mortal life

In the Fourth Gospel, Jesus is offering us an explicit Answer to some implicit Questions - but these Questions are no longer obvious to modern people, and it is worth drawing them out from the first half of the Fourth Gospel (chapters 1-12, up to The Passion) - and making them clearer. 

What Jesus offered, and how we are to accept it, is repeatedly stated in the Fourth Gospel - e.g. in the first and twentieth chapters: 1:12 - ...as many as received him, to them he gave power to becomes the sons of God, even to them that believe on his name.'; 20:31 - '...believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name.'

That is The Answer. But what was the Question? If we consider Jesus's main acts in the Fourth Gospel (of 'John'), the most heavily-emphasised events, then we can infer that he was addressing the basic, fundamental, essential problems of human life.

Some examples are: the discussion with Nicodemus about the need to be 'born-again'; the discussion with the Samaritan woman at Jacob's well about the water of life; healings of the nobleman's son at Cana, the cripple at Bethesda, and of the blind man; the cleansing of the Temple; the feeding of the five thousand; the woman taken in adultery; and the raising of Lazarus.

Although these certainly not reducible in significance to single implications; we can see that Jesus was addressing the fundamental problems of mortal human life: birth and death; trade and labour; family and sex; eating and drinking; disability and disease. He did not need (in those days) to emphasise that these were problems - everybody knew by experience.

So, briefly put; this is a message of the Gospel, in a Question and Answer, a Problem and Solution, form - the Answer of Jesus was to the fundamental problems of mortal life. Jesus was 'saving' us from the otherwise-insoluble problems of living.

The Answer was wholly and permanently by resurrection to life eternal; but also Jesus makes clear (for example in talking with the Samaritan woman) that insofar as we believe in him and on his name (the nature of his reality) here-and-now, we can experience (albeit only partly and temporarily) the joy of life everlasting even during mortal life.