There is a great spiritual chasm between the Son of God and an unsaved sinner. Back in the temple courts, Jesus explains this by stating two significant facts:

They have totally different origins (verse 23)
Naturally speaking, we are all part and parcel of this fallen world. Both literally and figuratively, that is where we are 'coming from'. Jesus comes and speaks from above (verses 26b, 28b-29). We cannot understand where he is 'coming from' (1 Corinthians 2:14). Only when we are converted are we 'raised with Christ'. Once we are 'coming from' the same place spiritually, we have a responsibility to 'set our minds on things above, not on earthly things' (Colossians 3:1-2). This inevitably involves a cost (John 15:18-19).

They have different destinations (verse 21)
Naturally speaking, we have different 'homes' to go to – heaven and hell. We must all go where we belong (Acts 1:25). Note that it is Jesus who is here speaking of those who will die in their sin and whom he will judge (verse 26). He speaks this way to break through their smug complacency. Though they reply flippantly (verse 22), what they say contains the grain of truth that he will lay down his life voluntarily for such sinners (John 10:18).

All this implies that the paths of the Son of God and unsaved sinners cross only briefly. The blind beggar of Luke 18:35-43 understood this well enough when he heard that Jesus of Nazareth was 'passing by' – and he made the most of his opportunity. Is that what we are doing? The key is whether or not we hold on to Jesus with a living faith.

Believing in who Jesus is
Read verse 24 of our passage. The words in brackets are not in the original. Jesus states that they must believe that 'I am', or they will die in their sins. This was an unmistakable reference to God himself. Jesus is claiming to be the same God who revealed himself to Moses at the burning bush as 'I AM WHO I AM' (Exodus 3:14). The Jews reply with utter disbelief: 'Who do you say you are?' Very soon they will be attempting to stone him for repeating this claim (verses 58-59).

Belief in a Jesus who is merely a great religious teacher or moral example is useless. The spiritual gulf created by our sin requires an infinitely more wonderful Saviour. The sin of unbelief at this point is the worst of all sins – because it is the sin against the cure of sin.

Believing in what Jesus has done
We must also trust in what Jesus has done for his people to remove the guilt, power and punishment of our sin. This is highlighted in verse 28. Jesus will deal with sin when he is lifted up on a cross. There he died in the place of all those who would trust in him down the ages – paying the penalty of their sin, so that they might go free.

But when Jesus speaks here of being 'lifted up' he means far more. He is thinking of all the cross will lead to: his resurrection, ascension, exaltation and return as Judge of all the earth. Then, everyone will know he is the Lord of glory (Philippians 2:5-11).

In verse 21, Jesus reminds us that it is possible to look for him in vain, or when it is too late. We must seek him with all our heart (Jeremiah 29:13). We must 'seek the Lord while he may be found; call on him while he is near' (Isaiah 55:6). Remember, as far as each one of us is concerned, he is simply 'passing by'.