Paul thanked God for changing him to enable Timothy to appreciate the fact that God can transform even the worst of sinners and enable His saints to accomplish supernatural feats. What called forth Paul"s testimony here was the difficult situation Timothy faced in Ephesus made even harder by Timothy"s personal tendency toward timidity. The evidence that Timothy tended to be timid, perhaps partly because of the strong opposition he faced, comes out more clearly later in this epistle. [source][source][source]
"V:11 with its assertion that the gospel was entrusted to Paul provides the setting for 1 Timothy 1:12-17. Paul demonstrates how this entrusting and his own reception of mercy and grace in Jesus Christ provides an illustration that the gospel is the power of God unto salvation for any sinner, because it has been that to him, a terrible sinner." [1][source]