What is the Most Important Claim of The Gospel?

The

• death 
• burial
• resurrection

is demonstrably the central claim of the gospel.

This shows the approximate fraction of each gospel is dedicated the final week of Jesus' life:

Matthew 21 out of 28 chapters before final week => 25% on final week
Mark 11 out of 16 chapters before the final week  => 31% on final week
Luke 20 out of 24 chapters before final week  => 16% on final week.
John 17 out of 25 chapters before the final week  =>  32% on final week.

Muslims see it as their mission to correct Christians' view by describing Jesus as "a prophet" (implying he is like other prophets).

But then why is there such an emphasis on the last week of the life of Jesus?  Jesus certainly was an Apostle, Prophet, Teacher, Evangelist, Pastor, (ministry gifts from Ephesians 4:11), but his primary mission was as as "Lamb of God who takes away the sin of the world"