The Miracles of Jesus as his Calling Card
Back in the day, people of status would have a calling card that they would leave at a place they visited if the person they sought was unavailable or absent. The card would have their name and appropriate contact information on it so that the person would know who had visited and how to reach them. The closest thing we have in these modern times would be a business card. Hold this thought until the end of this post.
Why do prophecies exist? That's easy. They exist so that we can recognise when the Lord fulfills each of his promises. The Lord loves humanity and he desires to lead us to our full potential and salvation. This explains why he didn't nuke us from space (because that's the only way to be sure). Rather, after Adam and Eve fell from grace, he activated a plan that he had from before he even made the universe (Revelation 13:8).
The first Messianic reference is generally agreed to be Genesis 3:15 (almost a miracle itself ... do you how hard it is to get theologians to agree on anything?). A descendant of Eve (Jesus) will defeat the serpent (the Devil / Lucifer). The Lord has been firm on his plan and telling us how it was going to turn out for as long as we humans have been on this planet of ours. I'm not going to list them all here, but there are many prophecies of the Messiah and almost every aspect of his arrival, ministry and death. Actually, both of his arrivals and ministries. This makes it very important to recognise when a prophecy speaks of his first or his second arrival. Getting these mixed up can cause serious errors in your theology, but that's best left to discus another day.
There are prophecies that speak of how we would recognise the Messiah when it was his time to walk among us. Not just things like him being born in Bethlehem (Micah 5:2) or born of a virgin (Isaiah 7:14), but more practical ways of identifying him. Prophecy tells us that the Messiah was going to perform miraculous healing: restoring hearing and sight (Isaiah 35:5), healing lame legs and restoring speaking (Isaiah 35:6), curing leprosy (Leviticus 14) and raising the dead (Isaiah 26:19). That’s a pretty clear and specific list of ways to identify the Messiah.
One of my favorite passages in the gospels is the one where John the Baptist is in jail and sends his disciples to ask Jesus if he's the one that they were waiting for (Luke 7:18-20). Jesus took no offense to the question, rather he immediately started healing infirmities and casting out spirits (Luke 7:21) and then asked John's disciples to report what they had seen (Luke 7:22-23). Why did Jesus do this? Because it was not unusual at that time for people to claim to be the Messiah (Acts 5:34-37). Anyone can make such a claim, especially if they have a charismatic nature and a good speaking voice, but publicly fulfilling all of the prophecies is a powerful statement of veracity. Jesus warned (Matthew 24:5) that many would claim to be the Christ, the New Testament term for Messiah, so the careful observation of fulfilled prophecies made sense to protect the soon to be founded church from false prophets.
While Jesus did verbally claim to be the Messiah on a number of occasions (Luke 4:16-21, John 4:25-26, Mark 14:61-62), for his cousin John the Baptist, he cut to the chase and demonstrated prophesied healings to John's disciples so that they would be eye-witnesses of these things. While John could not be there, as he was in prison, Jesus performed Messianic miracles to serve as his calling card for John. Where those miracles were performed, it was known that Jesus the Messiah had been there.