At this point we will leave our study in Acts to consider the two earliest epistles written to the church. The word epistle comes from the Greek word for "letter" or "missive," and simply refers to a letter sent from one person to another. We think of the New Testament as having epistles, but there are plenty of epistles in the Old Testament as well. Jeremiah 29 records an epistle from Jeremiah to the Babylonian exiles. Ezekiel 25–32 are evidently epistles sent by Ezekiel to the nations, calling them to repentance.
Why send letters? Are there theological aspects to the fact that the New Testament contains so many epistles? Yes. Consider the fact that the second person of the Trinity is the Word of God. God speaks His word, and God sent His Epistle to humanity to die for our sins. Now Jesus has ascended to heaven, and He sends Himself to us in the form of further words brought by the Holy Spirit.
We send a letter to make ourselves in some sense present to someone else. We can't be there in person, so we send a card or letter. Likewise, Jesus, now at God's right hand, is not here in the fullness of His person, so He has sent us a letter: the Bible. In the same way, the apostles sent letters. They could not be everywhere at once, so they sent letters to make themselves present to the churches.
Of course, by itself a letter is not always very personal. So Jesus has sent the Spirit along with His letter (the Bible) to make it personal for us. Similarly, we usually find that the apostles sent their letters by the hand of their assistants—their paracletes—so that these persons could help the readers have a well-rounded appreciation of the letter.
The apostles and their assistants are no longer with us. What remains for us is that Jesus is the ultimate Author of these epistles. They were sent from heaven to us. The Spirit came with them to deliver them, and continues to speak through them to His people.
There are two groups of epistles in the New Testament. The first consists of those by Paul, which are addressed to particular churches or persons. The second group consists of all the rest, which are called the catholic or general epistles because they are not addressed to particular churches or persons.
As you study the epistles over the coming months, occasionally think of what it must have been like to be in the early church receiving a letter from Paul or Peter or John. That same excitement and anticipation about what they would say should touch us today. Ask God to help you read those letters as if for the first time.