One way to counter a claim is to literally set up a counter claim. It is a lot easier to answer "how do you know this is true?" than "how do you know this is true, and not that?" Opponents of the Christian faith, especially atheists, are quite adept at this tactic. "How do you know Christianity is true, and not Islam?" Now I have to show Christianity is true and refute Islam, a religion you almost certainly don't believe anyway?
Far more tedious is when they bring up other alleged miracle workers. Thousands of people throughout history have claimed to be miracle workers, Messiahs, even gods. How do we know Jesus isn't "just" one of them?
One of the simplest ways is to ask "what other miracle workers?" People are quick to point out that other people have claimed to live miraculous lives, but no one ever actually names them. Why? Because they can't. They can't name other miracle workers, because Jesus, though being the least likely of them to succeed, is nevertheless the most successful.
Now, to cut off the straw man before it forms, I am not, and I repeat, not saying "He is successful, therefore He is the real deal". In fact, I'm really arguing the opposite. If these others had any merit to them, they would share Jesus' success. Their failure to do so eliminates them as credible contenders.
It's interesting that the Bible even mentions a few examples. In Acts 5, for example, a council was called to put the Apostles on trial, and a man named Gamaliel rose up to give his opinion. Theudas, and after him, Judas of Galilee, both claimed to be somebody, yet they died, and their disciples stopped preaching their messages. They failed.
But Jesus had the tenacity to exceed them, both in his posthumous success, and in the strength of His power. See, at most, failed miracle workers can do a few magic tricks. They can make a staff become a serpent, for example. But eventually, they reach the limit of their power, and even if they are priests of a completely different religion, they will sometimes confess "This is the finger of God." (Exodus 8:19).
But Jesus had no limit to His power. Not that He would display it on command, like some court jester to entertain the likes of Herod (Luke 23:6-12). Nevertheless, when Jesus performed a miracle, Jesus performed a miracle. He did things that we cannot do today. It is often said that you won't find faith healers working in a hospital. But Jesus healed things not even modern hospitals can. How does a first century carpenter heal a man who was blind since birth?
"By Satan's power!", said Jesus' contemporaries. Jesus' miracles were that good, His enemies chose to attribute them to Satan, rather than confess Him for who He was. But what does it mean when people attributed Jesus' miracles to Satan? It means He really was doing miracles. They didn't deny the act, they denied the source. It would be the same as if a modern atheist saw Jesus' miracles and said He was just a very skilled magician. That wouldn't be saying "Jesus didn't live a miraculous life", it would be saying "He did miracles, I just don't believe how He did them."
Of course, chief among these miracles is His resurrection, a feat literally no magician can pull off. Kill a magician, he's dead. He's not coming back. He's certainly not going to overcome Roman guards protecting his tomb. And neither could the disciples, which makes the prevailing myth of that age yet another strong evidence for Jesus' authenticity.
See, when you claim "the disciples stole the body", what you admit is Jesus' body was missing. Jesus was killed, Jesus was laid in a tomb, Jesus' tomb was heavily guarded by trained soldiers who would lose their very lives if they failed to guard His tomb, then Jesus was not in His tomb.
Now, you could make the argument that it's more likely the Roman guards risked their very lives for a power nap, and the disciples made quick use of this major lapse in security by stealing Jesus' body. It's kind of silly, but some might argue it's more plausible than a man literally rising from the dead. My next question is, what motive could they possibly have?
Christianity was literally born of persecution. Our God wasn't crucified for some revolutionary act of treason. They persecuted Jesus, and it was guaranteed that they would persecute His followers, too. If you ran around making baseless claims that Jesus had risen, you wouldn't gain anything. In fact, given how much of a nuisance Christianity was to basically anyone with any political or social power, it would have been infinitely more beneficial to anyone who could stop the movement to stop the movement. "Hey guys, we lied, this is where we hid the body".
But they never did. There is no record of a major lapse in the faith of anyone who devoted their lives to spreading the Gospel. Of course, being human, they did stumble occasionally, like in Galatians 2 when Peter, fearing the Jews, wasn't entirely open about the Gospel when among Gentiles. But even under fierce persecution, in spite of it being literally illegal, a capital offence, to preach that Jesus had risen, the Apostles all went to their graves for saying they saw Him alive.
Now, when you persecute a false movement, the chances are it's going to die the moment you strike the head. Theudas? He was killed, his followers scattered, his very name is preserved only in the pages of Scripture, and a short account written by Flavius Josephus. Judas of Galilee? Again, struck dead, and his movement fell. But when Jesus was struck dead, brutally murdered for all to see, people were willing to give their own lives for the testimony that He had risen again.
All of this puts Jesus far ahead of any failed Messiah. He did more impressive things, and that includes rising from the dead. Thus, rather than fizzling out after His death, Jesus' movement thrived under persecution. But on top of all of that, what you will find is that Jesus didn't just show up and start making claims. Rather, claims were made about Him centuries before He was even born. The Old Testament is littered with prophecies of a coming Messiah. And Jesus, and Jesus alone, fulfills them all. Furthermore, many of them are so explicit that you can read them without saying where you're reading from, and many people will automatically assume you are reading a description of Jesus from the New Testament. You can even read older Jewish literature and find that they often interpreted the Old Testament in similar ways to how Christians interpret it in light of the New Testament. No other failed Messiah is so accurately foreshadowed by any religious text! We cannot predict the outcome of an election that will take place in a week even half as well as the Old Testament predicted the life, death, and even resurrection of Jesus.
So, what makes Jesus different to other alleged miracle workers? Simply that He is the only one worth following. He was prophesied long before His birth. His miracles were so well known, even his enemies had to come up with alternative explanations. His miracles were so powerful, not even the best of our science can replicate them. His resurrection was so convincing, He had friends, and even ex-enemies like Paul, willing to die for affirming themselves as witnesses. Strike the head of a false movement, it dies. But when the head of the Church was struck, the Church only scattered until the third day.
All of this evidence leads us to the beautiful conclusion that when Jesus claimed those who believe in Him will not perish, but have eternal life, He has the power to follow through. Those who saw Him on the cross mocked "He can save others, let Him save Himself!" Well now we can say "He raised Himself, let Him raise others!" Everyone who confesses Him as Lord, and believes He rose from the dead, will likewise be raised incorruptible, and live forever in the Kingdom of Heaven. No "other" messiah can do that.