The sermons of Stephen and the apostles in Acts (excepting the farewell of Paul to the Ephesian Elders) are missionary addresses to outsiders, with a view to convert them to the Christian faith. The Epistles are addressed to baptized converts, and aim to strengthen them in their faith, and, by brotherly instruction, exhortation, rebuke, and consolation, to build up the church in all Christian graces on the historical foundation of the teaching and example of Christ. The prophets of the Old Testament delivered divine oracles to the people; the apostles of the New Testament wrote letters to the brethren, who shared with them the same faith and hope as members of Christ.
The readers are supposed to be already |in Christ,| saved and sanctified |in Christ,| and holding all their social and domestic relations and discharging their duties |in Christ.| They are |grown together| with Christ, sharing in his death, burial, and resurrection, and destined to reign and rule with him in glory forever. On the basis of this new relation, constituted by a creative act of divine grace, and sealed by baptism, they are warned against every sin and exhorted to every virtue. Every departure from their profession and calling implies double guilt and double danger of final ruin.
Occasions and calls for correspondence were abundant, and increased with the spread of Christianity over the Roman empire. The apostles could not be omnipresent and had to send messengers and letters to distant churches. They probably wrote many more letters than we possess, although we have good reason to suppose that the most important and permanently valuable are preserved. A former letter of Paul to the Corinthians is implied in 1 Cor.5:9: |I wrote to you in my epistle;| and traces of further correspondence are found in 1 Cor.16:3; 2 Cor.10:9; Eph.3:3. The letter |from Laodicea,| referred to in Col.4:16, is probably the encyclical Epistle to the Ephesians.
The Epistles of the New Testament are without a parallel in ancient literature, and yield in importance only to the Gospels, which stand higher, as Christ himself rises above the apostles. They are pastoral letters to congregations or individuals, beginning with an inscription and salutation, consisting of doctrinal expositions and practical exhortations and consolations, and concluding with personal intelligence, greetings, and benediction. They presuppose throughout the Gospel history, and often allude to the death and resurrection of Christ as the foundation of the church and the Christian hope. They were composed amidst incessant missionary labors and cares, under trial and persecution, some of them from prison, and yet they abound in joy and thanksgiving. They were mostly called forth by special emergencies, yet they suit all occasions. Tracts for the times, they are tracts for all times. Children of the fleeting moment, they contain truths of infinite moment. They compress more ideas in fewer words than any other writings, human or divine, excepting the Gospels. They discuss the highest themes which can challenge an immortal mind -- God, Christ, and the Spirit, sin and redemption, incarnation, atonement, regeneration, repentance, faith and good works, holy living and dying, the conversion of the world, the general judgment, eternal glory and bliss. And all this before humble little societies of poor, uncultured artisans, freedmen and slaves! And yet they are of more real and general value to the church than all the systems of theology from Origen to Schleiermacher -- yea, than all the confessions of faith. For eighteen hundred years they have nourished the faith of Christendom, and will continue to do so to the end of time. This is the best evidence of their divine inspiration.
The Epistles are divided into two groups, Catholic and Pauline. The first is more general; the second bears the strong imprint of the intense personality of the Apostle of the Gentiles.