In Matthew 26 verse 29 and 42, why does Jesus sound as if He is unsure or worried about being crucified if His main goal and purpose was to die for our sins?
In Matthew 26:29, the Lord is emphasizing that this is their last supper together. His crucifixion was just hours away. The "new" far more superior drink awaits them in the kingdom of God because He will have accomplished His mission of salvation for the human race.
In Matthew 26:42, the Lord reveals the anguish of His pain and suffering in the nature of His humanity. He was determined to save the world and willing submitted to the cross. He had to endure this shame, suffering, and brutal death in the flesh in order to fulfill Divine Justice. He knew that His pain was worth the gain of salvation for humanity. It is not realistic for a human to have no concern for suffering and death. Nonetheless, the Lord was determined to save us. He would have rather that humanity had not fallen and been sentenced to this death, but He willing accepted our bitter sentence as it was the only way to give us life.