Why was the learning process so difficult for the apostles? First of all, they lacked spiritual understanding. They were slow to hear and slow to understand. They were at various times thick, dull, stupid, and blind. All those terms or their equivalents are used to describe them in the New Testament. So how did Jesus remedy their lack of spiritual understanding? He just kept teaching. Even after His resurrection, He stayed forty days on earth. Acts 1:3 says that during that time He was “speaking of the things pertaining to the kingdom of God.” He was still persistently teaching them until the moment He ascended into heaven. A second problem that made the learning process difficult for the disciples is that they lacked humility. They were self-absorbed, self-centered, self-promoting, and proud. They spent an enormous amount of time arguing about who would be the greatest among them (Matthew 20:20–28; Mark 9:33–37; Luke 9:46). How did Jesus overcome their lack of humility? By being an example of humility to them. He washed their feet. He modeled servanthood. He humbled Himself, even unto the death of the cross.
Third, not only did they lack understanding and humility, but they also lacked faith. Four times in the Gospel of Matthew alone Jesus says to them, “O you of little faith” (6:30; 8:26; 14:31; 16:8). In Mark 4:40, He asked them, “How is it that you have no faith?” At the end of Mark’s Gospel, after they had spent months in intensive training with Jesus—even after He had risen from the dead—Mark writes, “He rebuked their unbelief and hardness of heart” (Mark 16:14). What remedy did Jesus have for their lack of faith? He kept doing miracles and wonderful works. The miracles were not primarily for the benefit of unbelievers; most of His miracles were deliberately done “in the presence of His disciples” so that their faith could be strengthened (John 20:30).
Fourth, they lacked commitment. While the crowds were cheering and the miracles were being multiplied, they were thrilled. But as soon as the soldiers came into the garden to arrest Jesus, they all forsook Him and fled (Mark 14:50). Their leader ended up denying Jesus and swearing he didn’t even know the man. How did Jesus remedy their proneness to defection? By interceding for them in prayer. John 17 records how Jesus prayed that they would remain ultimately faithful and that the Father would bring them to heaven (vv. 11–26).
Fifth, they lacked power. On their own, they were weak and helpless, especially when confronted with the enemy. There were times when they tried but could not cast out demons. Their faithlessness left them unable to harness the power that was available to them. What did Jesus do to remedy their weakness? On the day of Pentecost He sent the Holy Spirit to indwell and empower them. This was His promise to them: “You shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria, and to the end of the earth” (Acts 1:8). That promise was mightily fulfilled.
We’re inclined to look at this group with all their weaknesses and wonder why Jesus did not simply pick a different group of men. Why would He single out men with no understanding, no humility, no faith, no commitment, and no power? Simply this: His strength is made perfect in weakness (2 Corinthians 12:9). Again we see how He chooses the weak things of this world to confound the mighty. No one could ever examine this group of men and conclude that they did what they did because of their own innate abilities. There is no human explanation for the influence of the apostles. The glory goes to God alone.
from "Twelve Ordinary Men" by John MacArthur, Chapter 1
O that the Church would embrace who we are!
1 Corinthians 1
26 For consider your calling, brethren, that there were not many wise according to the flesh, not many mighty, not many noble; 27 but God has chosen the foolish things of the world to shame the wise, and God has chosen the weak things of the world to shame the things which are strong, 28 and the base things of the world and the despised God has chosen, the things that are not, so that He may nullify the things that are, 29 so that no man may boast before God. 30 But by His doing you are in Christ Jesus, who became to us wisdom from God, and righteousness and sanctification, and redemption, 31 so that, just as it is written, “LET HIM WHO BOASTS, BOAST IN THE LORD.”