What were the reasons for Jesus coming into the world? No doubt, many answers can be given to this question. John says three things here about the mission of Jesus. First, he came; second, he gave understanding to his people; and third, they come to know him.
When John says that the Son of God ‘has come’, he is referring to the coming of the Son at his incarnation when he added a human nature to his divine person. He became human without ceasing to be divine. He added a human nature to his divine Person, but his divine and human natures are not merged or combined. Instead he functions now and always will do so according to each nature.
The outcome of his coming is that his people have a proper grasp of reality. John here is referring to the office of Jesus as a prophet, our great teacher. His instruction is not at the level of our educational methods. Instead he teaches us through the Holy Spirit after giving us life by the Spirit. John does not say that this understanding is only for those with great intellects, even although there are deep truths to discover. The way we find the meaning of these truths is not by scratching our heads. Instead it is by spending time with our Teacher. We can see that this was the case with the first disciples selected by Jesus. Some of them would not have gone very far in a modern university class, but they discovered what cannot be known through all university classes without the help of Jesus.
The things concerning which Jesus has given us understanding are numerous. We understand that there is an eternity; we understand that there is an eternal God with a great plan of salvation; we understand that there is a problem called sin which God has dealt with; we understand that the Son of God became a man in order to die on the cross as the sinbearer and was raised again and has ascended to heaven to reign on the divine throne; and we understand that he is returning to raise the dead, to judge the world and renew the cosmos in order for God to dwell in it forever. That is some of the things that we understand. But whatever understanding we have we owe it all to Jesus.
The reason why we have this understanding is so that we would get to know Jesus. It looks as if both uses of the phrase ‘him who is true’ in this verse refer to Jesus rather than only the second. I suppose we can say that we get to know Jesus increasingly or gradually as well as getting to know him intimately. Paul’s desire as a mature Christian of many years’ experience was to grow in his knowledge of Jesus and to discover his power and care (Phil. 3:10). And we should have the same ambition.