1 Thessalonians 3:4

For verily, when we were with you, we told you beforehand that we are to suffer affliction; even as it came to pass, as ye know.

All Christians are servants of Jesus Christ and may expect the same treatment, wherever it is possible for the world to inflict it, that was received by the blessed Lord himself and his holy apostles. The warning that he gave the apostles (John 16:1,4) on the night he was betrayed has its application to Christians of all generations. "A servant is not greater than his Lord. If they persecuted me, they will persecute you, etc." (John 15:20).

Another thing in view here derives from the fact of Paul's indoctrination of the Thessalonian converts with information they were sure to need. As Ward said,

(Preachers) should teach basic doctrine to new converts and also prepare them for coming battles. In saying that "we" are on the road to affliction, the author was thinking of Christians generally.[12]