That miracles were performed in the days of our Lord's life here upon the earth is undisputable. Oh, yes, there are some who dispute them; there always have been doubters; and likely there always will be. Even as the signs were being performed, the Sadducees refused to believe that they were happening. (cf. Acts 23:8.) However, there is no explaining those things that happened except that it be miraculous.
Why were miracles performed? The text of Acts 2:22-24 offers an explanation. "Jesus of Nazareth, a man approved of God unto you by mighty works and wonders and signs which God did by him in the midst of you, even as ye yourselves know." So, we can see, that at least one reason for the miracles was to confirm the Sonship of Jesus. He was proven to be the Mesiah by those miracles that he did.
There were many more miracles than those we read about, but we know who some were recorded. "Many other signs therefore did Jesus in the presence of the disciples, which are not written in this book: but these are written, that ye may believe that Jesus is the Christ, the Son of God; and that believing ye may have life in his name" (John 20:30-31). Luke's record also confirms that the miracles performed had purpose. "But that ye may know that the Son of man hath authority on earth to forgive sins (he said unto him that was palsied), I say unto thee, Arise, and take up thy couch and go unto thy house" (Luke 5:24).
It was this fact that Peter spoke of on the day of Pentecost (Acts 2). Having referred to the confirming signs, he told those who were there, "Let all the house of Israel therefore know assuredly, that God hath made him both Lord and Christ, this Jesus whom ye crucified" (Acts 2:36). Then, in response to their query, he told them what they must do, and "They then that received his word were immersed: and there were added unto them in that day about three thousand souls" (Acts 2:41).
Yes, the fact that there were miracles performed by the Lord and others in the first century is undisputable. But, what about today? Are miracles necessary? No! The miracles of the first century did their work, and there is no need to continue confirming over and over those same things that have already been confirmed. Jesus is the Christ! That has been proven sufficiently for all who will hear; and it need not be proven again and again.