A.T. Robertson Commentary Acts 19:8

"And he entered into the synagogue, and spake boldly for the space of three months, reasoning and persuading [as to] the things concerning the kingdom of God." — Acts 19:8 (ASV)

Spake boldly (επαρρησιαζετο). Imperfect middle, kept on at it for three months. Cf. same word in 18:26.

Persuading (πειθων). Present active conative participle of πειθω, trying to persuade (28:23). Paul's idea of the Kingdom of God was the church of God which he (Jesus, God's Son) had purchased with his own blood (Acts 20:28, calling Christ God). Nowhere else had Paul apparently been able to speak so long in the synagogue without interruption unless it was so at Corinth. These Jews were already interested (18:30).