Let not your hearts be troubled. Believe in God; believe also in me. In my Father’s house are many rooms. If it were not so, would I have told you that I go to prepare a place for you? And if I go and prepare a place for you, I will come again and will take you to myself, that where I am you may be also. (John 14:1-3)
1) Sin needed to be atoned for! The wrath of God, the condemnation, the curse of God, was still unsatisfied. At that time, Jesus was about to become a curse for us (Galatians 3:13) and bear our condemnation (Romans 8:3) and became the acceptable and perfect sacrifice for sin (1 John 2:2)
2) Death needed to be defeated! Jesus was about to be the first fruit, the first resurrected from the dead (note that Lazarus was brought back to life but still had his mortal body).
Jesus said to her, “Your brother will rise again.” Martha answered, “I know he will rise again in the resurrection at the last day.” Jesus said to her, “I am the resurrection and the life. The one who believes in me will live, even though they die; and whoever lives by believing in me will never die. Do you believe this?”(John 11:25 & 26)