"Thus the death of Christ—the very event which the disciples had looked upon as the final destruction of their hope—was that which made it forever sure. While it had brought them a cruel disappointment, it was the climax of proof that their belief had been correct. The event that had filled them with mourning and despair was that which opened the door of hope to every child of Adam, and in which centered the future life and eternal happiness of all God's faithful ones in all the ages. GC 348.1"
"And if Christ be not raised, your faith is vain; ye are yet in your sins."
Both passages address the importance of Christ's death and resurrection. The EGW passage focuses on the disciples' initial despair turning into hope, while 1 Corinthians 15:17 emphasizes the futility of faith if Christ was not raised. They both highlight the crucial role of Christ's sacrifice in salvation.
Purposes of infinite mercy were reaching their fulfillment, even through the disappointment of the disciples. While their hearts had been won by the divine grace and power of His teaching, who “spake as never man spake,” yet intermingled with the pure gold of their love for Jesus, was the base alloy of worldly pride and selfish ambitions. Even in the Passover chamber, at that solemn hour when their Master was already entering the shadow of Gethsemane, there was “a strife among them, which of them should be accounted the greatest.” Luke 22:24 . Their vision was filled with the throne, the crown, and the glory, while just before them lay the shame and agony of the garden, the judgment hall, the cross of Calvary. It was their pride of heart, their thirst for worldly glory, that had led them to cling so tenaciously to the false teaching of their time, and to pass unheeded the Saviour's words showing the true nature of His kingdom, and pointing forward to His agony and death. And these erro…
"And there was also a strife among them, which of them should be accounted the greatest."
Ellen White directly references Luke 22:24 in this passage.