‘First, I thank my God through Jesus Christ for you all, that your faith is proclaimed throughout the whole world.'
He wants them first of all to know that he thanks ‘my God' through Jesus Christ for all of them, because he is aware that their faith is spoken of throughout the world. ‘My God' brings out the very personal feeling that Paul had for God. It also occurs in 1 Corinthians 1:4; Philippians 1:3. He saw Him as ‘my God', not because he was excessively possessive, but because his heart was so warmed towards Him. He felt in close association with Him.
And he thanked Him ‘through Jesus Christ'. This use here in Romans of the idea of Christ's mediatorship as related to his thanksgiving is unique. It is not introduced in his thanksgivings elsewhere. It probably arises in this case because of the nature of the introduction above, with its emphasis on ‘the Son'. He is continuing the emphasis on the Father's association with the Son, and on the fact that the Gospel of God is concerning His Son.
What he thanks God for is that ‘their faith is proclaimed throughout the whole world.' Whilst the words may contain a little flattery (he was trying to win their hearts so that they would give his words a fair hearing), they do also indicate the fact that the church in Rome was well known and well spoken of throughout the world with which Paul was familiar.
‘Your faith.' What is being spoken about is the strength of their trust in Jesus Christ. All knew of the vibrant faith of those in the church at Rome. And it had to be vibrant in order to survive what was brought against it.
It is important to note the phrase ‘throughout the whole world'. It is, of course, not literally true. There were many parts of the world where the Gospel had not reached. It was speaking rather of the world known to Paul. We can compare how ‘all the earth' came to hear the wisdom of Solomon' (1 Kings 10:24), that is all the world as known to the people of Jerusalem. The same proviso applies there. It means the world as known to the writer. This should always be borne in mind when we come across the word ‘world' in the New Testament and especially in Revelation. It is referring to the world known to the writer.