Disciples doubted?

If the Disciples of Jesus doubted why should you agree?.

It's funny when Christians claim the crucifixion was a fulfilment and the disciples were aware of it?? 

If that's the case why did they doubt? Surely they should of been waiting for such a fulfilment right! Why did Peter rebuke Jesus when Jesus apparently mentioned he has to suffer! Surely Peter should of accepted it right?? Unless he knew the messiah has to live and not get crucified!!!!  

Peter took him aside and began to rebuke him. "Never, Lord!" he said. "This shall never happen to you!" (Matthew 16:22)

Below is a few passages showing how the disciples doubted Jesus was crucified 

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When they heard that Jesus was alive and that she had seen him, they did not believe it. (Mark 16:11)

These returned and reported it to the rest; but they did not believe them either.

(Mark 16:13)

Later Jesus appeared to the Eleven as they were eating; he rebuked them for their lack of faith and their stubborn refusal to believe those who had seen him after he had risen. (Mark 16:14)

When they saw him, they worshiped him; but some doubted.

(Matthew 28:17)

But they did not believe the women, because their words seemed to them like nonsense. (Luke 24:11)

And while they yet believed not for joy, and wondered, he said unto them, Have ye here any meat? (Luke 24:41)