Paul normally opens his letters with a prayer of thanksgiving, conforming to the rhetorical style of the first century. In this introductory section, an author would normally praise his readers and introduce to them something of the plan of the letter. The “praise” section of the letter intends to put the readers in a positive frame of mind, more likely to accept the teaching that follows (see Wanamaker, 1-2 Thessalonians, 215). In this case, Paul praises his readers and then introduces the idea of the return of the Lord, the subject of the main section of the book
Paul begins by saying “we ought to always thank God for you….” The use of the word “ought” in this thanksgiving section is quite unique in Paul. ὀφείλω means “to be indebted” and it appears here in the thanksgiving section and in again in 2:13, another prayer of thanksgiving, This world therefore “frames” the first major section of the book.
Why would Paul say that he is obligated to praise the readers? It sounds a bit cold and perfunctory, especially in contrast to the warm praise offered in the first letter. It is possible that the praise Paul gave them in the first letter embarrassed them, they did not feel they were worthy of the high praise that Paul used in 1 Thessalonians 1.
The debt owed is not to the congregation, but rather to God. Since God is working in their church to develop fruit from the seeds he planted, it is his responsibility to praise God for the growth. Two specific areas are mentioned, faith and love. The third part of the familiar Pauline “faith-hope-love” is present in the next section when Paul outlines the hope of the believer in the soon return of Christ.
Their faith is growing. The verb for growing in this verse (ὑπεραυξάνω) is an intensive form of the normal word for growth. The word has a nuance of exceeding or abundant growth. The verb is in the present tense, indicating on-going growth. The church did not think that they had arrived spiritually and were no longer in need of any further growth. What growth that has occurred has been abundant, beyond expectations perhaps, but not yet perfection.
Their love is increasing. Like “growing,” increasing is a word which highlights the abundance of the growth (πλεονάζω). In 1 Thessalonians 3:12 Paul prays that the church experience an increase in their love “to the point of overflowing.” To some extent Paul is thanking God for answering his prayer, the church has continued to grow in love to the point of abundance. They are increasing in love for one another. The growth that is happening is drawing them closer together, the persecution that they are facing is making their congregation much more loving and supportive of the individual elements within the group.
Paul’s boast, therefore, may be an instruction to churches which have not yet been persecuted. When the difficult times come, be like the Thessalonians, whose faith grew stronger during times of persecution. The fact that their faith grew stronger during persecution should not surprise us. It is always the case that Christians in persecuted countries have a stronger faith that Christians in countries were Christianity is legal and popular. The persecution serves to focus the attention on what is important rather than on petty differences and minor points.
How would the church in America be different if it was facing a serious persecution? My guess is that it would be stronger, growing in love and faith. I also doubt we would be renovating malls or sports arenas either.