Martha believed, just as the Old Testament teaches, that there is to be a general resurrection at the last day, when everyone will be raised from the dead and judged according to their deeds during life on earth. Good people will be separated from bad people eternally. All that is very true.
But Jesus is here encouraging her to believe more than that. He desires her to understand that resurrection life is vested in Him. He is showing that it is their trust in Him for the forgiveness of their sins that makes people good in His sight; while the badness of the bad is characterised by their clinging to a righteousness of their own, according to how many good things they think they have done. He desires her to understand that He alone confers spiritual life by pardoning the repentant sinner freely.
Taking Lazarus, dead these four days, as an example, Jesus says that a loved one who has died believing in Him shall never die, but remain wonderfully alive in spirit. He demonstrates that He personally has the power to confer such life by bringing Lazarus back from the dead. Though Lazarus subsequently died, as we all must, Jesus declares by this miracle that He has the keys of death and hell and has opened the Kingdom of Heaven to all believers, past and present. All who have died as believers, remain alive in spirit. All live unto Him.
And whosoever liveth and believeth in Me shall never die. Believest thou this? She saith unto Him, Yea, Lord: I believe (John 11:26,27).
Jesus declares that a living believer, yet to pass through physical death, will never die. That is to say, at physical dissolution there will be no dying, but a glorious continuation of living awareness.
Believest thou this? Jesus put the question to Martha in the midst of her grief. He would not let her continue a moment longer in vagueness, but required some definite commitment, some 'homing in' of her latent faith. If the things of which Jesus speaks are not true, and He knew that to be so, what a monstrous torment to perpetrate on such a dearly loved and confiding friend! It is so preposterous as to offend reason. We are drawn to confess that, surely, Jesus speaks truly.
If it is a great help to believe these things in the circumstances of the death of a brother, how much more is it so when we contemplate our own death.
Jesus tenderly, but as truly, puts this question to us individually today by His Spirit, 'Believest thou this?' Surely our souls cry out, 'With all our hearts we do!'