Paul and his team had no doubt about the authenticity of the church in Thessalonica. They were brothers and sisters because they had been born again into the family of God through faith in Christ. That was the result of them welcoming the gospel message which brought conviction of sin – a mark of the Holy Spirit's activity on the people God is calling (John 16:8).
 
God's Word was not presented in a vacuum. God's servants (Paul, Silas and Timothy - as in 1 Thessalonians 1:1) had lived a different kind of life with different values which validated the gospel message which they brought. The gospel they preached was the same gospel they had believed. It transformed their lifestyle and was a great model for the new believers.
 
The apostolic team believed the gospel, lived the gospel and demonstrated the power of God in their lives. They were inspired by the Holy Spirit, presenting a compelling package of belief and behaviour which the Thessalonians wanted for themselves. They were not deterred by persecution or threats that worse lay ahead of them (Philippians 1:29). Indeed they were so full of joy which radiated to the city and beyond (1 Thessalonians 1:7-10).
 
The world does not need more good ideas. It needs to be convicted of sin by the Holy Spirit and saved through believing the gospel message, trusting in Jesus. When that message is accompanied by people whose lives have been changed by Jesus, others take notice; some will welcome the message and submit to Him (Titus 2:11-14). That should shape our roles as followers of Jesus: to understanding the gospel clearly, to repent and receive our Saviour as Lord and to learn to live His new life without fear. The workplace is a good place to practice, so that Jesus will be honoured and some will turn to Him.