Let me illustrate this from my work in theological education. For a number of years I ran a program of theological education that operated by distance learning. We would write study guides, send them out to our students around southern Africa, and then twice a year I would go to various places and meet with the students. During our classes and seminars I would never say to the students, Now that I am with you in person, you can forget about the study guide; that is just a dead letter.
I would always tell them to take out their study guides and would explain to them what was written there. In the same way God has given us the message of the gospel, which for us is recorded in Scripture. By his Spirit God enables us to understand that message and, as in the case of the Thessalonians, to be convinced that it is true—with the result that we are enabled to repent and believe the gospel. This has important implications for our preaching of the gospel.
5 because our gospel came to you not only in word, but also in power and in the Holy Spirit and with full conviction. You know what kind of men we proved to be among you for your sake.