In many questions of motivation, we need to depend on inferences from human nature, patterns of behavior, and from cultural norms. There are also direct quotes from scripture that shouldn’t be ignored, especially the words of Jesus.
The disciples of Jesus were ordinary young men, not stained-glass windows! They were zealous, strong-willed, ambitious, suffering from “testosterone poisoning,” and hadn’t yet been filled with the Holy Spirit, which was only going to come later at the Feast of Harvest (Acts 2:1-4).
Consider the following:
• Vernard Eller makes a strong case (stronger than you might think) in his book, The Beloved Disciple that the disciple “whom Jesus loved” was Lazarus, who also wrote the Gospel of John, perhaps in collaboration with John. However, in John 11, it’s written that Jesus loved Martha, Mary, and Lazarus. In Mark 10:21, it’s written that Jesus loved the rich young ruler, and Jesus loved all his disciples according to John 13 and 15. Yet in John 19, we see a reference to “the disciple whom he loved” and gave his mother into this disciple’s care. Yes, I’m aware of early Christian attribution to John. Lazarus might have been John’s scribe as Mark was Peter’s scribe.
• The disciples were competitive, ambitious, and jealous of each other on occasion.
Competitive
Both of them were running together, but the other disciple outran
Peter and reached the tomb first. - John 20:4 ESV
Ambitious
And [Jesus] he said to her, “What do you want?” She said to him, “Say
that these two sons of mine [James and John] are to sit, one at your
right hand and one at your left, in your kingdom.” – Matthew 20:21 ESV
Ambitious
An argument arose among them as to which of them was the greatest. But
Jesus, knowing the reasoning of their hearts, took a child and put him
by his side and said to them, “Whoever receives this child in my name
receives me, and whoever receives me receives him who sent me. For he
who is least among you all is the one who is great.” – Luke 9:46-48
ESV
Jealous
And when the [other] ten heard it, they were indignant at the two
brothers. – Matthew 20:24 ESV
Jealous – Peter was jealous regarding “the disciple whom Jesus loved” regarding whether he would die:
When Peter saw him, he said to Jesus, “Lord, what about this man?”
Jesus said to him, “If it is my will that he remain until I come, what
is that to you? You follow me!” So the saying spread abroad among the
brothers that this disciple was not to die; yet Jesus did not say to
him that he was not to die, but, “If it is my will that he remain
until I come, what is that to you?” – John 20:21-23 ESV
Vernard Eller suggests that this is more plausible that the disciples would speculate whether Lazarus, having already been dead and resurrected would die a second time.
Misogynistic
Women were oppressed under the Judean, Greek, and Roman cultures. For example, at the end of Jesus’ interaction with the Samaritan woman, it is written
Just then his disciples came back. They marveled that he was talking
with a woman, but no one said, “What do you seek?” or, “Why are you
talking with her?” – John 7:7 ESV
The disciples didn't try to cover their shortcomings, but admitted to them. They can teach us a lot from their mistakes and failures as well as their victories.
For he knows our frame; he remembers that we are dust. - Psalms 103:14
ESV
There's significant discussion regarding the ending of John and how disjointed it seems (specifically, chapter 20). This has led some to hypothesize that John's gospel has been edited a few times. These could be insertions from the Johannine community revising an original document.– swasheck May 02 '12 at 21:36