Paul began the first main section of his epistle by reviewing several aspects of the Thessalonians" salvation and giving thanks to God for them to encourage his readers to persevere despite persecution. [source][source][source]
". . . both letters name Paul, Silas, and Timothy as the authors of the letters. Yet the letters are traditionally ascribed to Paul alone. Is this fair? Many scholars answer no. They note the way the first-person plural dominates both letters, even in the thanksgiving section, which does not happen in most of the other Pauline letters, including three of them that name someone else in the salutation ( 1 Corinthians ,, Philippians , Philemon). The inclusion of more than one person in the salutation of a letter was most unusual in antiquity; readers would probably have read the plural "we" as a genuine indication of authorship. However, there is reason to pause before drawing this conclusion. ... Paul is the primary author [1]." [2][source]
"Paul, like a good psychologist, and with true Christian tact, begins with praise even when he meant to move on to rebuke." [3][source]