Let’s look at some Scripture for our answer. Before they died, Jesus told the thief that they would be together in Paradise on THAT VERY DAY. Jesus could not have meant Heaven. After all, in John 20:17 (several days later, after His resurrection) Jesus told Mary that He had not yet ascended to His Father…so Paradise cannot be heaven.
What is Paradise?
Let’s go to Luke 16:19-31…the story of Lazarus and the rich man. Here Jesus tells of “Abraham’s Bosom” and “Hades”…the waiting places of the righteous and unrighteous dead, respectively. There’s a gulf fixed between them that prohibits crossing over, but they are adjoined. The two together were known as Paradise.
1 Peter 3:18-20 tells us that after Jesus died He went and made proclamation to the spirits now in prison, who once were disobedient in the days of Noah. That prison is Hades, which is part of Paradise. Hades is more literally translated “the grave”. The translation to “hell” is an unfortunate one, as hell is not yet populated. So: Jesus told the truth to Mary about not yet ascending to His Father…and He told the truth to the thief about being together in Paradise THAT DAY. Peter’s words give further evidence that this explanation is accurate.