Their testimony was so close in time to the event itself that any number of witnesses could have denied their veracity.
How could they hope to fake accounts of events that would have taken place in the most well-known and observed places? So much of Jesus’ ministry was in Jerusalem, at the temple, the marketplaces, pools, fountains, highways & byways of the people. He was tried in Jerusalem & crucified just outside the gate & buried nearby. Thousands must have been witnesses to all of this.
Do fabricated accounts name names? And big names, too! Annas, the father-in-law of Caiphas, the high priest & Caiphas himself are named. The entire Sanhedrin, Herod Antipas, tetrarch of Galilee & Perea, Nicodemus, a well-known Pharisee, Joseph of Arimathea, a man of wealth & prominence not to mention Pilate himself, the Roman governor. These are all in the accounts with great detail. No, you don’t make up stories about such widely known folks when so many were still around who could easily expose your lies.
How humiliating to write that Jesus gave them multiple warnings about what would happen and that not one of them believed him? How foolish they would seem to write that not one of them was there at the tomb on the 3rd day to see Jesus resurrected. Would they have exposed themselves to be such cowards noting how they fled their Lord in the garden when he needed them the most & denied him with cursing? Would they make up a story that showed them to be faithless, when the whole point of the story was to convince others to believe?
And what man living in the culture of first century Judaism would have thought it a good idea to say that the first ones to see the risen Christ were women? What a scandal when these ladies, considered second-class citizens, would see Jesus before any of the apostles. To compound the humiliation, the record says when the women told apostles they were mocked by them for claiming that Jesus had risen from the dead. Yes, who would make up such a story?
Why would you accept the record of the resurrection of Jesus by those, who by their own admission, were reticent to accept it?
Maybe because you would see that the only way they would be compelled to report all of this the way they did, is because it actually happened.