‘And for this cause we also thank God without ceasing, that, when you received from us the word of the message, even the word of God, you accepted it, not as the word of men, but as it is in truth, the word of God, which also works in you who believe.'
‘And for this cause --.' This looks back to what he has been saying, and forward to the description of the Thessalonian response. Paul and companions have preached faithfully and pastored faithfully. Now he rejoices that the Thessalonians responded faithfully. We have already seen how closely he links his powerful ministry and their equally powerful response (1 Thessalonians 1:4-6).
‘We also thank God without ceasing.' Compare 1 Thessalonians 1:2-3 a. Paul's gratitude to God overflows. The Thessalonian continued response had been a great encouragement to him after the hard time he had had at Athens where response had been limited (Acts 17:17-34), which had caused him much pause for thought (1 Corinthians 2:3).
‘That, when you received from us the word of the message, even the word of God, you accepted it, not as the word of men, but as it is in truth, the word of God, which also is working in you who believe.'
There is an interesting contrast here between receiving (paralambano) a message outwardly, and receiving it (dechomai) and fully responding to it inwardly, thus ‘accepting' it.
‘The word of the message', or ‘the word that was heard'. Akoe can mean the faculty of hearing, the act of hearing or listening, that which was heard, the preaching. Thus the emphasis here is on hearing without indicating the response (which is included in the next verb). ‘Even the word of God.' The phrase is literally ‘having received the word of hearing from us of God'. What they heard was ‘of God'.
‘You accepted it.' They received it into their hearts and responded to it. Why? Precisely because they recognised it for what it truly was, not man's word but God's word. And that word is now continually at work within them through the effective working of God because they are in a state of continually believing, they are ‘believing ones'. Thus they need have no doubt of Paul's credentials for they are still experiencing within the effects of the message he proclaimed. But he has really moved on from concentration on defence. That is no longer his emphasis. He is now rather rejoicing in what has been accomplished.