A friend had taken my church's challenge to read through the New Testament this year and asked about Matthew 27:51-53, which reads:
51 At that moment the curtain of the temple was torn in two from top to bottom. The earth shook, the rocks split 52 and the tombs broke open. The bodies of many holy people who had died were raised to life. 53 They came out of the tombs after Jesus’ resurrection and went into the holy city and appeared to many people.
Commentators like D.A. Carson argue this was done in order for those present to better understand the death and resurrection of Christ. Jesus' sacrifice was the "death of death" for those who place their faith in the Lord.
I know this raises more questions, so let me give it a shot. As Dr. Michael Bird points out in his fine "Evangelical Theology," the Bible teaches that all those who die before the death and resurrection of Christ went to Sheol, the place of the dead. It was divided into two places--the resting place of the righteous and the unrighteous. The former was known as "paradise." This is why Jesus states on the cross to one of the thieves crucified with him, "Today you will with me in paradise." (Luke 23:43).
No one, not even the righteous like Abraham, Moses, David, etc. could enter heaven unless they had first been covered with the blood of Christ. Paradise is where Jesus went to preach to the righteous and then take them to heaven with him when he ascended back to His Father.
Dr. James R. White argued that those resurrected (and notice it was AFTER He emerged from the tomb) would likely have been the recently deceased because they were recognized. Dr. White speculates it could have been Simeon and Anna (Luke 2). Whether he is right or not, the point is that Jesus conquered death for those who have faith in Him.
Hope that answers the question. Tune back in daily for more.