The apostles have preached the Gospel to us from the Lord Jesus Christ; Jesus Christ [has done so] from God. Christ therefore was sent forth by God, and the apostles by Christ. Both these appointments, then, were made in an orderly way, according to the will of God. Having therefore received their orders, and being fully assured by the resurrection of our Lord Jesus Christ, and established in the word of God, with full assurance of the Holy Ghost, they went forth proclaiming that the kingdom of God was at hand. (1 Clement 42)The belief of the first century church was that God sent forth His Word, Jesus. Jesus then selected those whom He would call Apostles that He might teach them His message. He then sent them out into the world to teach His message to all who would believe. In so doing, the Apostles became the definitive and decisive source and authority on God's message for mankind.
The fact that God would send forth Apostles to proclaim His message was prophesied long ago. Jesus reminds us, "For this reason also the wisdom of God said, 'I will send to them prophets and apostles.'" (Luke 11:49) Also, Jude concurs with the idea that the God's message has once and for all been delivered to mankind."I felt the necessity to write to you appealing that you contend earnestly for the faith which was once for all handed down to the saints." (Jude 3) In the first century church they understood that the delivery of this message, once and for all, was to the Apostles; they were entrusted with it and it was their responsibility to teach it to the world. In their minds, the Apostles had received the full and complete message of faith, once and for all.
When we understand this then we begin to understand some other scriptures. For example,
"They were continually devoting themselves to the apostles' teaching and to fellowship, to the breaking of bread and to prayer." (Acts 2:42)It was not just teaching they were devoted to, but the teachings of the apostles. The early church would never ask if an idea or teaching was biblical or scriptural, but rather if it was apostolic; does it conform to the teaching and message of the Apostles. A church or teacher was considered apostolic if they taught and maintained the teachings and traditions of the Apostles. The Apostolic church was first a church that was orthodox as pertaining to the things the Apostles taught and commanded.
Another scripture that becomes clearer when we understand how the early church viewed the Apostles is,
"Am I not free? Am I not an apostle? Have I not seen Jesus our Lord? Are you not my work in the Lord? If to others I am not an apostle, at least I am to you; for you are the seal of my apostleship in the Lord." (1 Corinthians 9:1-2)Paul maintains that, in regards to the Gospel, he "neither received it from man, nor was I taught it, but I received it through a revelation of Jesus Christ." (Galatians 1:12) The Apostles were not simply passing on what they had heard, they were taught the Gospel directly from Jesus. This is a distinguishing mark of an Apostle, a disciple who was personally taught the message of God in a face-to-face meeting with Jesus. This is what brought the Apostles their authority and the authority of their teachings. They could be believed because Jesus Himself had personally taught them His message.
This also brings to light the importance of what John said,
"What was from the beginning, what we have heard, what we have seen with our eyes, what we have looked at and touched with our hands, concerning the Word of Life — and the life was manifested, and we have seen and testify and proclaim to you the eternal life, which was with the Father and was manifested to us — what we have seen and heard we proclaim to you also, so that you too may have fellowship with us; and indeed our fellowship is with the Father, and with His Son Jesus Christ. These things we write, so that our joy may be made complete." (1 John 1:1-4)The Apostle's teachings are not just something they heard in the past, nor the machinations of an evil mind sent to enslave us in some cleverly devised heresy, rather is is the message of God, delivered once and for all, face-to-face to the Apostles of our faith. Our faith rest confidently in them and there message that it is the true message of God for the world.