The fact that seven of the readings for the Easter Vigil are from the Hebrew Scriptures shows how quickly after Jesus' death and resurrection the Easter Vigil developed. Communities in the earliest Church always used Jewish writings to help understand their experiences of Jesus.
And because the experience we celebrate in this liturgy is the one essential Christian experience -- dying/rising -- we logically expect our passages from the Hebrew Scriptures to revolve around that theme. It isn't enough to celebrate life; we celebrate life from death.
Saved by God
The Hebrew Scriptures' event which best commemorates that phenomenon is the Exodus from Egypt (Ex 14:15-15:1). Squeezed into an impossible situation by advancing Egyptians and the sea, the escaping Israelites are certain they'll either be slaughtered or drowned. At this point, Moses contradicts their good sense, ordering them to step into the one element which guarantees death: the sea.
"Tell the Israelites to go forward!" Yahweh commands. When against all logic, the Chosen People follow God's command, they discover that, instead of drowning, they're marching "into the midst of the sea on dry land, with the water like a wall to their right and to their left." The very thing which should have killed them, saves them.
Such an experience caused our ancestors in the faith to remember that their escape from Egypt wasn't the first time Yahweh had brought life from death. Abraham had experienced a parallel phenomenon when he followed Yahweh's command to sacrifice Isaac, his only son (Gen. 22:1-18). God had ordered the first person who believed in God to offer as a holocaust the one individual who guaranteed that Abraham's name would live on forever and that his descendants would one day take over Canaan. If Isaac dies, then Abraham and his dreams die.
Yet just as Abraham is about to strike the fatal blow, Yahweh intervenes. "Do not do the least thing to him," God commands. "I know now how devoted you are to God, since you did not withhold from me your own beloved son." By being willing to lose what is most dear, the follower of God attains what is most dear.
Followers of Jesus can testify to the truth of that statement -- not because they've read about it, but because they've experienced it. So we shouldn't be amazed at contradictions in the Gospel accounts of the empty tomb. Only Matthew, for instance, speaks about guards at the site, seals on the stone, an earthquake and a "sky-diving" angel (Mt 28:1-10). In their narratives of the empty tomb, each evangelist mirrors the experiences of the community for whom he writes. No one passes through death into life in exactly the same way. We'll always differ one from another in how we express that reality.
Yet one basic message underlies the Christian dying/rising experience. "I know you are looking for Jesus the crucified, but He is not here. He has been raised, exactly as He promised. Come and see the spot where He was laid."
It's that experience which prompts Paul to remind the Church in Rome (a Church which he didn't evangelize) of the belief all Christians share (Rom 6:3-11). "Are you not aware," he writes, "that we who were baptized into Christ Jesus were baptized into His death?...If we have been united with Him through likeness to His death, so shall we be through a like resurrection."
The early Church would have been befuddled by our modern attempts to prove that Jesus really rose from the dead. Why would anyone spend time and effort trying to prove the evident? They knew Jesus rose, not because they had a video of the event, but because when they imitated His death, they rose. When they totally lost themselves in love for others, they found themselves. When they stepped into the sure death of sacrificing themselves, as Jesus had, they discovered they were given a deeper, more meaningful life than they could ever have achieved by avoiding such a death.
The first Christians celebrated the Easter Vigil not because it reminded them of Jesus' dying and rising, but because it reminded them of their own dying and rising.