These are some of the things we know about Judas Iscariot:
- Judas was chosen as one of the 12 (Luke 6:12-16; Mark 3:13-19).
- He was sent out as one of the 12 (Matthew 10:4).
- He accompanied Jesus with the other 11 disciples, beheld the Lord's character and power and heard Him teach and claim to be the Messiah (Mark 3:14).
- Judas never declared Jesus as Messiah; never came to faith in Jesus as his Messiah (John 6:64-65; 13:10-11, 18; 17:12).
- He put in charge of the money (John 12:6; 13:29).
- Judas stole money (John 12:6).
- When Mary anointed Jesus's feet of Jesus, Judas was enraged by her extravagant gift, which could have been sold for a significant price; managed to convince his fellow disciples to verbally harass Mary (John 12:1-8; Matthew 26:6-13; Mark 14:3-9).
- At this time, the chief priests and Pharisees were panic-stricken by Jesus's growing popularity (John 11:45-53, 57; 12:9-11). They wanted to seize Jesus privately, but not during the feast of Passover because they would stir up the crowds (Matthew 26:3-5; Mark 14:1-2). They became so desperate they decided to kill not only Jesus (John 11:53), but Lazarus as well (John 12:10). The time was ripe for Judas to come to them with his proposal of betrayal.
- Shortly after this incident with Mary, in which Jesus rebuked Judas and the other disciples, Judas went to the chief priests and stuck a deal to betray Jesus (Matthew 26:14-15; Mark 14:10-11).
- Judas looked for the right moment to hand Jesus over (Mark 14:11).
- Judas was with Jesus and the disciples during the first part of the Last Supper, in a place of honor, next to Jesus (John 13:26).
- At the meal, Jesus indicated that one of the disciples would betray Him (Matthew 26:20-25; Mark 14:1721) and showed it would be Judas (Mark 14:20; John 13:21-27).
- Judas accepted the bread from Jesus. After which, Satan entered him (John 13:27).
- Jesus dismissed Judas to carry out his terrible deed (John 13:27-30).
- Judas led the soldiers to Jesus, where he betrayed Him with a kiss (Matthew 26:47-50; Mark 14:43-46; Luke 22:47-48; John 18:1-9).
- Judas regretted his betrayal and tried to reverse his actions by returning the money, but it is too late. (Matthew 27:3).
- Judas hung himself (Matthew 27:3-10; Acts 1:15-19).
Although Judas isn't mentioned often in the Gospels, we do know he was sent out to perform miracles just like the other 11 disciples. Amazing!
Mark 10:1 says, "And he called to him his twelve disciples and gave them authority over unclean spirits, to cast them out, and to heal every disease and every affliction."
Judas witnessed firsthand the miracles of Jesus. He ate with Him. Fellowshipped with Him. Was given power to cast out demons and heal the sick. He witnessed Jesus walking on water, feeding the 5000, then the 4,000.
Every other disciple grew in their faith at each new manifestation of our Lord's power, love, mercy, and holiness. But not Judas. Still, it wasn't obvious to the disciples that Jesus was speaking of Judas when He said one of them would betray Him.
And just how could Judas do this after all he'd seen and heard? Because it doesn't matter if God Himself is sitting right next to you, if the Lord doesn't open your spiritual eyes, you will never understand, you will never recognize Him.
But wouldn't the disciples have noticed that Judas wasn't growing spiritually? Wouldn't they have noticed the lack of spiritual fruit in his life?
In fact, when Jesus said one of them would betray him, they didn't point fingers at Judas and say, "I knew it!" Instead, they asked, "Surely not I, Lord?" (Matthew 26:22)
I believe he was like his father, the devil, disguised as a "servant of righteousness" (2 Corinthians 11:13-15).
In James Boices's commentary he pointed out that, "Judas teaches us that sinners need more than a good example to be saved. Judas had the best example who has ever lived, but he was still dead in his trespasses and sins (Eph. 2:1). Unless the Holy Spirit imparts new life, sinners are not capable of repenting of sin, believing in Christ, and reforming their lives. That is why Jesus told Nicodemus (John 3:7), "Do not be amazed that I said to you, 'You must be born again.'" 
Like Judas, there are those today who have spent time surrounded by believers, who may be actively involved in ministry, and yet, don't know Jesus as Savior and Lord.
Before he encountered Jesus on the road to Damascus, Paul (then Saul) was a religious man, doing what he believed God would have him do. But he came to realize everything except truly knowing Christ was garbage (Philippians 3:1-11).
Judas was a hypocrite. And hypocrites can put on a good show. They can fool man, but they can never fool God. Even today, we shouldn't be surprised when so-called men and women of God fall away from the faith. God knew their heart all along. We should keep our eyes on Jesus, not on those who fall away.
I wouldn't be surprised if Judas was on John's mind when he wrote, "They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us"
(1 John 2:19).
Judas's betrayal should serve as a cautionary tale. Just why did he follow Jesus? Like so many others, I believe he misunderstood what Jesus had come to accomplish. He probably felt Jesus would become a political Messiah and usher in a new era of health, wealth, and prosperity. But when Jesus didn't line up with his expectations, Judas began to pull away.
The crowds followed Jesus, but He wouldn't entrust Himself to them. He knew they were looking for a political ruler to deliver them from their Roman oppressors.
The people got really upset at Jesus because not only did He say He was greater than Moses but also that He was equal to God (John 6:35-40). This destroyed all their preconceived ideas regarding the Messiah. So, they refused to believe it and walked away. Jesus knew they had false faith, He knew they didn't truly believe. And the hard truth revealed their heart.
It's right after this, right after the massive crowd left Jesus and the only ones left were the disciples that Peter said, "You have the words of eternal life, and we have believed, and have come to know, that you are the Holy One of God."
In verse 70, Jesus responded, "Did I not choose you, the twelve? And yet one of you is a devil."
Then John gives us some commentary in verse 71. He says, "He
[Jesus] spoke of Judas the son of Simon Iscariot, for he, one of the twelve, was going to betray him."
I think John waited until this moment to bring up Judas to show us what started it all. Judas stopped believing in Jesus because Jesus didn't meet his expectations. In his heart, he became just like the crowd and figuratively walked away from Jesus.
Why do you follow Jesus? Most of us come to Him for selfish reasons. We either have a need or desire and we hope Jesus can meet those needs. But what happens when things don't work out like we expect? What do we do when we don't experience health, wealth, and prosperity but, instead, experience hardship, heartache, and trials? Will we become like Judas or will we repent of our false expectations and embrace Jesus for who He really is?
 The Gospel of John
[Zondervan], 1-vol. ed., p. 894