"That they may believe that you sent me."

Then Jesus, deeply moved again, came to the tomb. It was a cave, and a stone lay against it. Jesus said, “Take away the stone.” Martha, the sister of the dead man, said to him, “Lord, by this time there will be an odor, for he has been dead four days.” Jesus said to her, “Did I not tell you that if you believed you would see the glory of God?” So they took away the stone. And Jesus lifted up his eyes and said, “Father, I thank you that you have heard me. I knew that you always hear me, but I said this on account of the people standing around, that they may believe that you sent me.” When he had said these things, he cried out with a loud voice, “Lazarus, come out.” The man who had died came out, his hands and feet bound with linen strips, and his face wrapped with a cloth. Jesus said to them, “Unbind him, and let him go.” Jn 11:38-45
“Do not marvel at this, for an hour is coming when all who are in the tombs will hear his voice and come out, those who have done good to the resurrection of life, and those who have done evil to the resurrection of judgment. Jn 5:28-29”
The resurrection of Lazarus is but a foreshadowing of this hour. That the dead would be raised was a sign that Jesus gave to the distressed John by which the Messiah could be known. The dead will be raised up. The New Testament has numerous occasions of this happening in Jesus ministry. But not everyone who dies is raised up. Lazarus is the only one who is called out of the grave. Jesus does this sign just days before his entrance into Jerusalem, just days before his crucifixion. It is a sign that John the Baptist does not get to see, but one that his disciples do get to see. It is one last boost of faith before the trials begin. In another week, it will be overshadowed by Christ’s own resurrection, a resurrection to eternal life.
But on the last day, the hour will come, and all who are in the grave, all the dead of the world, will hear the voice of Jesus and come forth out of the ocean, out of the dirt, they will be raised up from there ashes and brought forth to meet their maker. Then we will walk out as Lazarus, at his voice to the resurrection of life. And those who have refused Jesus, to the resurrection of Judgment.