"The thief cometh not, but for to steal, and to kill, and to destroy: I am come that they might have life, and that they might have it more abundantly." (John 10: 10)
Jesus did not come that we would keep the lives that we have now, but just make it better.
On this earth, from the moment we step into this world, we are dead in our trespasses (Ephesians 2: 1).
Jesus came to make dead people live:
"For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life." (John 3: 16)
Then Jesus declared:
"Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me." (John 14: 6)
Jesus now lives in every believer:
"Even the mystery which hath been hid from ages and from generations, but now is made manifest to his saints:
"To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory:" (Colossians 1: 26-27)
"For ye are dead, and your life is hid with Christ in God.
"When Christ, who is our life, shall appear, then shall ye also appear with him in glory." (Colossians 3: 3-4)
God did not want to make our earthly lives better. He sent His Son to give us His life.