'Why people don't believe Him, I just can't understand.'
John 11:24-26New King James Version (NKJV)
24 Martha said to Him, “I know that he will rise again in the resurrection at the last day.”
25 Jesus said to her, “I am the resurrection and the life. He who believes in Me, though he may die, he shall live.
26 And whoever lives and believes in Me shall never die. Do you believe this?”
Christ says He is the resurrection and He is the life and that those who are alive in Him and believe in Him will never die. For someone to be the resurrection, for one qualification, they would have to die and come back to life. So yeah, believing Christ is the resurrection and the life is of critical importance, for it the dead are not raised ,then your faith is in vain because Christ says in Him you will be resurrected.
Revelation 1:18
I
am He who lives, and was dead, and behold, I am alive forevermore. Amen. And I have the keys of Hades and of Death.