Paul points to the boldness he had from God to preach the gospel to the Thessalonians, despite having just recently been beaten and imprisoned in Philippi. Because of his and Silas’ continued faithfulness, they were able to bring many Philippians (even their jailer) to belief in Jesus, and were ultimately set free. Paul’s perspective is to endure suffering for the gospel because this allows him to share in the sufferings of Christ, which will be rewarded by Jesus when He returns. This gives him and his team courage to continue preaching the good news of the savior.
He seems to answer criticisms that have been levied against him: he did not preach the gospel to the Thessalonians out of ignorance, impure motives, deception, flattering speech, greed, or for man’s praise. Nor did he take food or money from them, but supported himself while preaching to them. In reality, he and his team preached the gospel as gently as nursing mothers taking care of their dear children. He treated the Thessalonians well and did not take advantage of them, so that he has credibility when he encourages them, like a loving father would, to continue to walk with God.
Paul tells the Thessalonians that they are suffering just as the churches in Judea do under persecution from people who oppose God. This suffering is to be expected, and endured with perseverance and continued faithfulness. Paul misses the Thessalonians and wishes he could see them again because they are his hope and joy as he looks forward to the day Jesus returns.