The body of Jesus had disappeared from the tomb (Matthew 28:6).  Despite the seal on the gravestone and the guards to protect the way into the burial site, the body had gone because Jesus was alive … death could not hold Him (Acts 2:24).  The divine removal of the stone was not to let Jesus out, but to let the witnesses in (John 20:3-8; Acts 3:15).
 
However, that gave the religious leaders a problem.  They thought that the influence of Jesus, and particularly His challenge to their authority, would die away after His crucifixion.  Nevertheless, they had anticipated that if His disciples could steal His body, they might pretend that He was alive, as He promised.  That is why the chief priests wanted Pilate's authority to post some of the temple guards to prevent that happening (Matthew 27:62-64).  But they could not stop Jesus rising.  So, they resorted to lying.
 
They made up a story and bribed the guards to admit that they fell asleep on duty, and yet somehow they knew (despite their unconsciousness) that the disciples had stolen the body!  It was a very unlikely report.  If it had been true, the guards should have been most severely punished for their incompetence.  The large sums of money that they gained should have alerted somebody that there was another story.  But it suited everybody involved to be blind to logic and truth.  It suited the people who wanted Jesus to die to believe the lies.  But key witnesses knew the living Jesus was alive (1 Corinthians 15:3-8), and the deception was unmasked.
 
Without the resurrection, Jesus would have been just another man who died.  But so many eye-witnesses met Jesus after the resurrection that it should be impossible for right thinking people to deny its truth.  However, the old lies continue to circulate.  Why should people not want to be objective?  Simply, it does not suit them: they do not want to accept that Jesus is King … they do not want to admit that they are sinners who need a Saviour to rescue them from God's wrath … they do not want to repent and submit to Him … they want to pretend that they are in control of their destiny and can achieve all they need without Jesus.  So they believe a lie (2 Thessalonians 2:9-12).  The only way to unmask a lie is to tell the truth.  That is the ongoing work of Jesus' church (Acts 1:8).  Wherever you hear people telling lies about Jesus, tell the truth: so that they may believe in Him and be saved (www.crosscheck.org.uk).