The church was growing rapidly and dispersed through the nations around the Mediterranean Sea. Both in Jerusalem and in the churches founded by missionaries or Christians fleeing persecution, there was a need for sound teaching and a way to bind them together into the larger body of Christ. The epistles served this purpose.
The epistles cover a lot of ground. Some of them are fairly long and heavy on instruction. Others are short, more newsy and encouraging. Themes that I find recurring in the epistles are: a reiteration of the Gospel emphasizing the centrality of Christ, living as a Christian with character and good relationships, and words of warning and encouragement.
Reiterating the Gospel: The Centrality of Christ
The epistles repeatedly summarize the Gospel. We have all sinned. Christ came to atone for our sins through His death on the Cross. His righteousness is imputed to those who receive Him. He was resurrected, as foretold, as proof of that He was Christ and as evidence of the resurrection we will experience.
The epistle-writers vigorously defended who they knew Christ to be. He was God (he was divine, God-the-Son, a person of the godhead). He was incarnated; God became flesh and lived as a human being. He died on the cross, physically dying as a man. He was resurrected, and that resurrection was a bodily restoration and transformation, not merely a spiritual continuance.
Christian Living: Character and Relationships
Now that these Christians were saved, what did it mean for the way they lived? This is still an important question for Christians. We are to abandon sin and do what is right, exhibiting a Christ-like character. That character is typified by faith, self-control, humility, and especially love.
One of the toughest problems we face in life, and one of the most important, is our relationships. The epistle-writers address how we are to relate to each other in church, marriage, family, work, and business.
Warning and Encouragement
The early church was beset by false teachers. These people twisted the scripture to suit their own purposes. It has not stopped. These letters warn us to look out for falsehood and show us how to spot it.
Even more than this, though, these letters are full of encouragement. We are not alone; God is with us always as the Holy Spirit indwells us. Whatever trials, temptations, or opposition we face, we can live the life God has called us to in Christ. Not only that, the difficulties we face in ourselves and around us in this sinful world will pass, and we will be resurrected to live forever in the perfect love and peace of God.
The epistles are: