Paul was also grateful that his readers had demonstrated the fruit of their faith by becoming followers of their teachers and their Lord. They had welcomed the gospel message even though it had meant much suffering for them because of the persecution of unbelieving Jews and Gentiles. Most of the New Testament writers took for granted that tribulation is the normal experience of Christians (cf. John 16:33; Acts 14:22). Nevertheless with tribulation joy had also come to them, the joy of sins forgiven. News of their good example had circulated within their own province of Macedonia but had also reached their neighboring province to the south, Achaia. This excellent example included generously giving to other Christians in need ( 2 Corinthians 8:1-8). [source][source][source]
"This is high praise, for in the first place Paul calls no other church a pattern, and in the second he thinks of them as examples, not only to the heathen, but to Christians throughout Greece." [1][source]