The Best Workers of the Harvest
And when I inspired the Apostles: "Believe in Me and My Messenger [Jesus]"; they said, "We believe; witness Thou our submission."' [Quran, 5:111]
All prophets and messengers of God have had some chief enemies and opponents, who made them suffer all kinds of troubles and difficulties and, in most cases, murdered them in the end.
On the other hand, they all had their close companions and disciples who devotedly followed their instructions and guided the believers during their time and after their demise. Unfortunately, this group is usually not as large as it needs to be!
The harvest is plentiful, but the workers are few. Ask the Lord of the harvest, therefore, to send out workers to His harvest field. [Matthew, 3:37,38]
Take Them for Examples!
The Disciples of Jesus are especially important in Islamic tradition. They are basically mentioned as exemplary faithful and devoted characters and the helpers of Jesus with his mission. This inspires Muslims to return that everlasting call in the way the Disciples did, and say: "We, too, are God's helpers." And God definitely supports His helpers!
O you who have faith! Be God’s helpers, just as Jesus son of Mary said to his disciples, ‘Who will be my helpers for God’s sake?’ The Disciples said, ‘We will be God’s helpers!’ So a group of the Children of Israel believed, and a group disbelieved. Then We strengthened the faithful against their enemies, and they came to prevail [over them]. [Quran, 61:14]
Neither Pride, nor Weakness, nor Doubt
According to Islamic narrations, the Disciples (Hawariyyun in Arabic) were called so since they were pure in themselves, and purified others from the filth of sin, by sermons and remembrance of God. 
Describing the Disciples of Jesus, Prophet Muhammad said:
They were those chosen by him as best and they were twelve who were unmarried and quick to help God and His Messenger. There was neither pride in them nor weakness nor doubt. They helped him [Jesus] with vision, influence, seriousness, and suffering. 
Do not Get Angry
Some other Islamic narrations quote the conversations between Jesus and his Disciples. For example, the Disciples once asked Jesus:"O teacher of good, tell us what the most severe of things is." "The most severe of things is the wrath of God," he replied. "And what prevents the wrath of God?" the Disciples asked again. Jesus said:
That you may not be wrathful. 
According to the words of Prophet Muhammad, Christianity fell into different sects after Jesus. And those who followed Simon Peter, the greatest Disciple who was ordained by Jesus, went the right way and were saved. 
Islamic narrations also recount some acts of the apostles. It is narrated that Jesus sent two of his Disciples to Antioch. Hearing about them, the king sent for them and asked them about their signs. They said: "We heal the blind and the leper by God's leave, and we ask you to worship God the One." But the idolater king was not pleased and imprisoned them.
Jesus, then, sent Simon Peter after them. He acted so wisely that, soon, became close to the king and was fully trusted. So, Simon once talked to the king about the two prisoners and asked him to bring them to him. When they were brought to Simon, he asked, "What is the god you worship?" They said, "God (God the One)." He said, "Does He hear you and answer you when you pray to Him and ask for something?" The answer was affirmative.
So, Simon asked them to heal a leper and so they did. Then Simon asked them to heal a blind and so they did (some narrations say that Simon also did the same). Finally, Simon asked them if they could revive the dead, and they answered yes. Simon faced the king and said, "Is there a dead person whose passing has been hard for you?" "My son," the king said, and took them to his grave.
The two prisoners raised their hands in prayer as did Simon. And then, the grave suddenly cracked open and the youth stood up. He faced his father who asked him, "How are you?" He answered, "I was dead and terrified when I understood there to be three persons standing before God with their hands raised in prayer to Him. They prayed that He revives me. They were those two and he."
Simon said, "I am a believer in your God." The king said, "O Simon, I believe in Him in Whom you have come to believe." And finally, none remained in Antioch who did not believe. 
This story is also mentioned in the Quran, 36:13,14:
Cite for them the example of the inhabitants of the town when the apostles came to it. When We sent to them two [apostles], they impugned both of them. Then We reinforced them with a third, and they said, ‘We have indeed been sent to you.’