holy kiss: The kiss was a common Jewish greeting, not just a sign of personal affection. It was common in the New Testament church (Romans 16:16; 1 Corinthians 16:20; 1 Thessalonians 5:26; 1 Peter 5:14). It may have held significance in worship services by uniting fellow believers (the "kiss of peace"). The word for sacred (Greek hagiō) is the same word translated as God’s people (literally the saints; Greek hagioi) in the next sentence.
God’s people here were the believers in the place where Paul was writing in Macedonia.