1 Thessalonians 2:2
But though we had already suffered and been shamefully treated at Philippi, as you know, we had boldness in our God to declare to you the gospel of God in spite of great opposition — Paul's willingness to suffer is the proof of his sincerity; perseverance through persecution authenticates his message. The 'boldness' (parrēsia) is not arrogance but the confident speech of those seized by divine truth. Opposition does not silence but amplifies the gospel's urgency.