Lazarus had been in the tomb for four days when Jesus finally arrived (John 11:17). When Lazarus had fallen ill, his sisters, Mary and Martha, sent word to Jesus. Now, Jesus loved Lazarus and his sisters, but instead of immediately going to see his friend, He said that Lazarus' illness would not lead to death, but that it was for the glory of God, so that the Son of God would be glorified through it (John 11:1-6). Now, I'm sure that these were not exactly the words that Mary and Martha had hoped to hear. They likely hoped that Jesus would come immediately and heal their brother. But now their brother was dead.
When Jesus arrived, Martha went out to meet Him. Perhaps out of anger, frustration, or simply because of the grief she felt at the loss of her brother, Martha's first words to Jesus were, "Lord, if only You had gotten here sooner, then maybe my brother would still be alive! (John 11:20-21)" Martha knew that Jesus had the power to heal the sick and was disappointed that He had not been there to heal her brother. If Jesus had been there, then her brother would not be sealed in a tomb. Martha also knew that God would give Jesus whatever He asked for (John 11:22), but did she believe He could raise someone from the dead? Since she responded to Jesus' statement that Lazarus would rise again by saying that, yes, he would, at the last day when everyone else rises (John 11:23-24), it seems likely that she didn't believe that Jesus would raise Lazarus right then and there. But that is just what Jesus did (John 11:43-44)!
Jesus said that He is the resurrection and the life. He said that those who believe in Him will live, even after they die. And everyone who lives and believes in Him will never die (John 11:25-26). When sin entered the world through man's disobedience to God, death came with it. But when Jesus died and rose again, He conquered both sin and death. There are two kinds of death, a natural death, and a spiritual death. We will all one day face a natural death, but when we believe in Jesus, believe that He died for us and that He rose again, and we turn from sin to follow Him, we will not face spiritual death but will live in eternity with Him. Just as Lazarus was dead and Jesus raised him from the grave of natural death, we were dead in our sin and Jesus has raised us from the grave of spiritual death.