Hebrews 3:1 (KJV) Wherefore, holy brethren, partakers of the heavenly calling, consider the Apostle and High Priest of our profession, Christ Jesus;
The word apostle has been transferred directly from the Greek without translation: apostolos (αποστολος)  meaning messenger or delegate, rendered messenger in 2 Corinthians 8:23. Note also the definite article " the apostle", for Christ was not just any apostle but the one and only begotten of the Father. Since Christ is the apostle we should be able to find characteristics of his apostleship and indeed the instructions (mission) bestowed upon him.
The Gospel of John reveals five "missions" Christ came to fulfil:
John 3:17 (KJV) For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
Christ came to his own to save them. He was the light come to the dark world. His mindset was to save. Judgement will come, but this was not at this time, for grace offers salvation before righteousness demands judgement.
Our mission is not to judge the world, its wickedness, its rebellionness, stubbornness, arrogance, iniquity or idolatry, but to bring the gospel to the lost. For the gospel is the power of God to salvation (Romans 2).
John 3:34 (NIV) For the one whom God has sent speaks the words of God, for God gives the Spirit without limit.
Prophets who came before Jesus spoke the words of God with various degrees of truthfulness. Christ came in all perfectiveness and spoke the exact words His father gave him. Christ had heard and seen his Father and came and spoke those very words he had heard and seen ("I speak to the world those things which I have heard of him [the Father]" John 8:26, also v.38). Indeed the commandments he spoke were exactly as the father gave him to speak (John 12:50). He spoke the words of the father so his joy could spill over into us (John 17).
Our mission is to speak the gospel without waving, without adding to it or taking from it or withholding any part of it. And the commandment of those that preach the gospel is that they need to live the gospel:
1 Corinthians 9:14 (KJV) Even so hath the Lord ordained that they which preach the gospel should live of the gospel.
John 4:34 (NIV) 34"My food," said Jesus, "is to do the will of him who sent me and to finish his work.
Christ, from early childhood to the cross ("Did not you know that I must be about My Father's business?") he had the mindset and heart attitude to do his father's will, not some of it, nor additions to it, but all of it . Up to this point the Father had been working, Christ came to finish it - and it was finished.
Hence, we understand that we are saved because of the will of him who was sent: "By that will we have been sanctified through the offering of the body of Jesus Christ once for all" Hebrew 10:10.
John 5:36 (NKJV) 36But I have a greater witness than John's; for the works which the Father has given Me to finish-the very works that I do-bear witness of Me, that the Father has sent Me.
The work the Father began is finished my Jesus. His mission was to perform this work, in complete accordance to the will of the Father. He neither deviated right nor left in doing this. He had a plan and a goal, which was set by the Father. This he tenaciously kept to and fulfilled.
In response to John the Baptist, Christ summarises his mission up to that point:
The blind receive their sight and the lame walk, the lepers are cleansed, and the deaf hear, the dead are raised up, and the poor have the gospel preached to them. Matthew 11:5 (KJV).
John 17:6 (NKJV) "I have manifested Your name to the men whom You have given Me out of the world. They were Yours, You gave them to Me, and they have kept Your word.
The task has not been complete, for the command was given for the gospel to go out and preach repentance and remission of sins.
Luke 24:46,47 (KJV) And said unto them, Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day: And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem .
This command was not been rescinded, for indeed the time is to come when the fulfilment of the great commission become evident (Matthew 28:19).
 G652 Strong's Concordance