(Luke doesn't like to talk about the failures of the disciples. He excuses their sleep, saying it was "from grief.")
Twice in the last six verses Jesus tells the disciples to pray that they may not undergo the test. This is the same Greek word Luke used earlier for Jesus' temptation in the desert, and in the Our Father when Jesus said, "... lead us not into temptation."
What is this "test/temptation?" It's not your run-of-the-mill king. It's the big one. Is there a God, really? Is evil going to win after all? Am I wasting my time trying to lead a decent life? At death, do I simply dissolve into nothingness?
You can't go through life without having these kinds of doubts, probably more than once. Jesus faced this question head-on with the devil in the desert, and he's facing it here in Gethsemane.
It's a good topic for conversation with the Lord. He was truly human, and had to deal with human thoughts and feelings. It wasn't always a waltz.
Not that we disbelieve the great truths. It's just that our belief sometimes has holes in it. When Jesus told the father of the sick boy to have faith, the father replied with words we can make our own: "I do believe. Help my unbelief." (Mark 9:24)
- Little Black Book, Diocese of Saginaw