The Apostles wavered in their faith in Jesus as the Messiah, because they anticipated and desired to see in Him an earthly king, in whose kingdom they could sit at the right and the left hand of the Lord.
The thief understood that the Kingdom of Jesus of Nazareth, despised and given over to a shameful death, was not of this world. And it was precisely this Kingdom that the thief now sought: the gates of earthly life were closing after him; opening before him was eternity. He had settled his accounts with life on earth, and now he thought of life eternal. And here, at the threshold of eternity, he began to understand the vanity of earthly glory and earthly kingdoms. He recognized that greatness consists in righteousness, and in the righteous, blamelessly tortured Jesus he saw the King of Righteousness. The thief did not ask Him for glory in an earthly kingdom but for the salvation of his soul.
The faith of the thief, born of his esteem for Christ’s moral greatness, proved stronger than the faith of the Apostles, who although captivated by the loftiness of Christ’s teaching, based their faith to a still greater extent on the signs and wonders He wrought.
Now there was no miraculous deliverance of Christ from His enemies — and the Apostles’ faith was shaken.
But the patience He exhibited, His absolute forgiveness, and the faith that His Heavenly Father heard Him so clearly, indicated Jesus’ righteousness, His moral superiority, that one seeking spiritual and moral rebirth could not be shaken.
And this is precisely what the thief, aware of the depth of his fall, craved. He did not ask to sit at the right or the left hand of Christ in His Kingdom, but, conscious of his unworthiness, he asked in humility simply that he be remembered in His Kingdom, that he he be given even the lowest place.
+ St. John Maximovitch of Shanghai and San Franscisco, From Man of God: Saint John of Shanghai & San Francisco, “Why the Wise Thief Was Pardoned”