Maybe the story should be defined first.
Matt 27 and
Mark 15 declare that
BOTH thieves mocked and made fun of Jesus.
SO answer this:
How can one robber be saved in Luke but both robbers mocked Jesus in Matt and Mark?
Mark 15:32 Let Christ the King of Israel descend now from the cross, that we may see and believe. And
they that were crucified with him reviled him.
Matt 27:44 The robber
s who had been crucified with Him were also insulting Him with the same words.
Should you define what happened before you argue about what it means?