Just as we open our letters today with the conventional "Dear John," so Paul begins his letters in the way that was characteristic of the casual Greek letter of his day: A to B, greetings. How he elaborates this typical opening provides us with insight into his uppermost concerns at the time of writing (see the introduction). In 2 Corinthians Paul's concerns are three in number: (1) his apostleship, (2) God's ownership of the Corinthian congregation and (3) the church as the family of God.
The Sender (1:1) Paul's foremost concern is his apostolic standing in the Corinthian community. The very lack of elaboration in comparison with Paul's other letters highlights this at the start: Paul, an apostle of Christ Jesus by the will of God. The first-century writer used this part of the letter to strengthen family ties and friendships. Paul is no different. This is clear from his references to Timothy our brother (v. 1), together with all the saints (v. 1) and our Father (v. 2), by which he seeks to reinforce the idea of the church as the family of God.
The Readers (1:1) Corinth is distinguished, both in this letter and in 1 Corinthians, with the unique address to the church of God. The singular church, in contrast to the more commonly found all and saints, focuses attention on the unity of believers in the Corinthian locality. Of God emphasizes divine ownership--an ownership that differentiates the church from a culture and society that were centered on idolatry (see the introduction).
It was common in Paul's day to include others beyond the immediate readers as independent witnesses of a letter's content and reception--somewhat like the function of our notary today. In the case of 2 Corinthians, all the saints throughout Achaia are called on to verify Paul's claim of apostleship--a claim that has been challenged from both inside and outside the Corinthian church and which, as we will see, Paul is at pains to defend throughout the letter.
The Greeting (1:2) Paul's greeting takes the form of an ancient Near Eastern blessing: Grace (or "mercy" in Jewish letters) and peace. Normally at this point, the first-century writer would go on to wish his reader(s) good health--much as we say, "Hope all is going well." Paul, instead, specifies the source of good health for the believer--God our Father and the Lord Jesus Christ. It is this kind of Christian blessing that he invariably uses to round off his opening greeting. God as a source of peace would be a typical Jewish thought. Our Father, however, brings Paul's greeting into the sphere of the familial--the exact way Jesus taught his disciples to address God in prayer. Yet, it is to be noted that while God is our Father, Jesus is not here spoken of as "our brother" but, rather, the Lord.Kyrios is placed first for emphasis. Grace and peace come from the Lord Jesus Christ. The concept of God as Father of the church and Jesus as her Lord captures too key distinctives of the Christian faith.
So Paul in these opening verses seeks to highlight both his apostolic and his family relationship to the Corinthians by calling on the witness of the broader community of Achaian believers and pointing to the filial bonds he and the Corinthians share. By making this most personal of letters "public," Paul holds the Corinthians accountable to the church at large.