The Gospel Quotes
I am attempting to distinguish these quotes about the Gospel from quotes about salvation.
If you are a Christian, you should read Decoding Nicea. Read why here.
The Gospel is the proclamation of Jesus of Nazareth as God's Anointed King. Both the word "Messiah" (Heb. meshiach) and the word "Christ" (Gr. christos) mean "one who is anointed." It takes very little searching to find that all priests, some prophets, and all kings were anointed in ancient Israel.
There are very few specific references to "The Anointed" (the Messiah/Christ) in the Hebrew Scriptures (Old Testament). The clearest is Psalm 2, which gives a description that any Christian will recognize as an exact description of our belief about Jesus.
The best way to prove that the Gospel is the proclamation that Jesus is King, and specifically that he is the promised Anointed King of Psalm 2, is to ask you to read through Acts in your Bible. You will see there that unlike modern evangelists, the apostles never preached the atonement. Though they emphasized Jesus' death for our sins in the letters to the churches, they never told a single lost person that the forgiveness of sins had anything to do with Jesus' death. Instead, Jesus' death was only mentioned in order to bring up his resurrection, a resurrection that proved that he was God's Anointed King (e.g. Acts 2:32-36).
This is the reason we are told repeatedly that the apostles' main purpose is to be witnesses of the resurrection (e.g., Acts 1:22; 2:32; 4:33). This is also why the Scriptures say that God gives his Spirit to the ones who obey him (Acts 5:32; Heb. 5:9). The faith that the apostles call us to exercise is belief in the Gospel, and the Gospel is the announcement that Jesus is God's Anointed King who will reign forever and judge both the living and the dead (Acts 17:30-31).
There is a true, biblical theology of salvation, and there is a true, biblical theology of the atonement, but while both are good and important for the Christian to know, neither constitutes the Gospel.
There are many quotes addressing this below, but I have also written a booklet outlining each of the apostles' sermons in the book of Acts, called The Apostles' Gospel. If you are up for an in-depth study of the Gospel of the Kingdom, you need to try Matthew Bryan's Forgotten Gospel.
Not many of my quote pages have an introduction like this, but this one is very important (cf. Gal. 1:8-9).
Clement of Rome, A.D. 96
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 (cf. Rom. 10:15). (First Clement 42)
Ignatius, AD 107 or 116
We also love the prophets because they too have made reference to the Gospel, hoped in him, and awaited him, in whom also, through believing, they were saved in union with Jesus Christ, worthy of love and admiration, saints well spoken of by Jesus Christ, and numbered with us in the Gospel of the common hope. (Letter to the Philadelphians 5)
I exhort you to do nothing out of strife, but according to the teaching of Christ. When I heard some saying, "If I do not find it in the ancient writings [or, possibly, "the archives"], I will not believe the Gospel. On my saying to them, "It is written," they answered me, "That remains to be proven." But to me the ancient writings are Jesus Christ. The sacred archives are his cross, his death, his resurrection, and the faith which is through him. In these things I desire, through your prayers, to be justified. (Letter to the Philadelphians 8)
The priests are indeed good, but the High Priest is better, to whom the holy of holies has been committed, and who alone has been trusted with the secrets of God. He is the door of the Father, by which enter Abraham, Isaac, Jacob, and the prophets, apostles, and the Church. All of these are brought into the unity of God. But the Gospel has something distinctive: the appearance of the Savior, our Lord Jesus the King, his suffering and resurrection. For, beloved, the prophets preached about him, but the consummation of the Gospel is immortality. (Letter to the Philadelphians 9)
Polycarp, A.D. 125-155
If, then, we entreat the Lord to forgive us, we ought also to forgive as well, for we are before the eyes of our Lord and God, and "we must all appear at the judgment seat of Christ, and each one must give an account of himself" [Rom. 14:10-12; 2 Cor. 5:10]. Let us then serve him in fear and with all reverence, just as he himself has commanded us, and as the apostles who preached the Gospel to us, as well as the prophets who proclaimed in advance the coming of the Lord. Let us be zealous in the pursuit of what is good, keeping ourselves from causing offense, from false brothers, and from those who bear the name of the Lord in hypocrisy and draw vain men away into error. (Letter to the Philippians 6)
Martyrdom of Polycarp, AD 160-170
We do not commend those who give themselves up [to martyrdom], seeing the Gospel does not teach us to do so. (Martyrdom of Polycarp 4)
Irenaeus, AD 183-186
The Lord says to the disciples, "Therefore every scribe, which is instructed in the kingdom of heaven is like a man that is a master of the house, who brings out of his treasure things new and old" [Matt. 13:52]. ... He called his disciples "scribes" and "teachers of the kingdom of heaven." ... Now, without contradiction, by those things which are brought from the treasure new and old he means the two covenants. The old is that giving of the law which took place in the past, and he points out as the new that manner of life required by the Gospel. (Against Heresies IV:9:1)
N.T. Wright, 1997
When Paul says 'the gospel', he does not mean 'justification by faith'; he means the message, the royal announcement, of Jesus Christ as Lord. (What Saint Paul Really Said, pp. 125-126)
But if we come to Paul with these questions in mind — the questions about how human beings come into a living and saving relationship with the living and saving God — it is not justification that springs to his lips or pen. When he describes how persons, finding themselves confronted with the act of God in Christ, come to appropriate that act for themselves, he has a clear train of thought, repeated at various points. The message about Jesus and his cross and resurrection — 'the gospel', in terms of our previous chapters — is announced to them; through this means, God works by his Spirit upon their hearts; as a result, they come to believe the message; they join the Christian community through baptism, and begin to share in its common life and its common way of life. That is how people come into relationship with the living God. (What Saint Paul Really Said, pp. 116-117)
Britt Mooney, 2011
The Gospel was more than just an individual plan of salvation. It was the expression of a meta-narrative that invited the individual to join the story as a disciple and a participant in the story. A simple plan of salvation invites one to make a single decision, to become converts. The Gospel as a meta-narrative makes disciples, which was the commission of Christ to the apostles and the Church. The understanding of the Gospel in such a way leads to a creation of a community of disciples, a veritable “gospel culture” in churches. ("The Patristic Rule of Faith as a Guide to Modern Evangelical Unity"; [a term paper shared with me by the author])
David Williams, 2014
Over the last seven years I have become increasingly convinced that the message which the apostles proclaimed as “the gospel” was not sola fide but Kyrios Christos, "Christ is Lord." That is to say, the gospel is, properly speaking, the royal announcement that Jesus of Nazareth is the God of Israel's promised Messiah, the King of kings and Lord of lords. (David Williams. "What is the Gospel?: Sola Fide, Kyrios Christos, Christus Victor?" 30 July 2014. Ten Thousand Places. Accessed 10/10/2014.)