When the modern reader of the Gospels reflects on the work of Jesus during His three years of mission and, as John wrote at the end of his Gospel: 'The disciples saw Jesus do many other miraculous signs in addition to the ones recorded in this book', then the question must be asked, 'Why is this or that recorded?' For example, it appears that some of the events recorded demonstrate Christ's power over sea, wind and storm. Others reveal His great compassion and His desire to do things quietly if at all possible. Miracles such as the feeding of the five thousand revealed to the Jews that the man standing before them was superior even to the Old Testament greats, such as Moses and Elijah.
Why the recording of this particular miracle then? Let's look at it in detail:
Jesus was travelling from Tyre to the area around the Sea of Galilee, home territory. Now, if you were to study a map you would note that Jesus began a journey from Tyre in the north to Galilee in the south by going due north , similar to going from London to Cornwall via Manchester. The way Jesus did it, the journey could have taken weeks, as the distance was greater than one hundred kilometres! Again, we can ask 'Why?' It is probable that this was the opportunity for Jesus to spend time quietly with His disciples before the storm breaks: He knew what awaited Him if He returned to Jerusalem, but there would be problems even in Galilee. We can notice the effects this long journey with the disciples had on them when we study the end of the next chapter and Peter's declaration- probably on behalf of the group- that Jesus was the Anointed One.
Anyway, when Jesus arrives back to Decapolis, a man is brought to Jesus who is deaf and struggling to speak. He takes him aside from the crowd and demonstrates to him what He is going to do by putting His hands in the man's ears and touching his tongue with saliva. He then looked up to heaven to proclaim by action that this healing was straight from God and the man could hear and speak! Jesus had dealt with the man in a way that spared his feelings and in a way that he could understand.
The reaction of the crowd echoed the verdict of God on His creation in Genesis 1 v 31 and this then emphasises that Jesus had begun the work of creation all over again: bringing healing to broken bodies and salvation to human souls.