Moving the goalposts is an informal fallacy in which evidence presented in response to a claim is dismissed and greater evidence is demanded, in order to invalidate the initial evidence. 

Example: An atheist asks, “What evidence do you have for the resurrection of Jesus?”

To which the Christian replies, “1) That Jesus was buried in a tomb by Joseph of Arimathea. 2) That on the third day, Jesus’ tomb was found empty by a group of Jesus’ women disciples. 3) That there were post-mortem appearances of Jesus, alive, by followers, unbelievers, enemies, as well as individual sightings and group eye-witnesses. 4) The the Christian faith grew rapidly in Jerusalem; where all these occurrences took place.”

To which the atheist insists, “Well, extraordinary claims require extra ordinary evidence.”

Thus, moving the goalpost.