Exposing false teachings, correcting understanding and refuting false accusations can be done using Biblical doctrine.
Stephen: Acts 6:8-7:60
Stephen is one of the first deacons and part of what he did was dispute with members of the synagogue of the Libertines (6:8-9). This is an interesting synagogue since the reference to Cilicia (where Tarsus was located) and his appearance later means that this was probably the synagogue Saul was a member of and overseen by the Gamaliel the Pharisee (see Acts 5:34-40), teacher of Paul (see Acts 22:3).
The key verse for this first part is verse 10: And they were not able to resist the wisdom and the Spirit by which he spake. There were two things mentioned, wisdom and Spirit. Spirit we know as Christians, but what is this wisdom? Since Spirit is already mentioned, it isn't the speaking of the Spirit, it must be something else.
After being refuted the Jews paid off people to be false witnesses while seizing and dragging Stephen before the council to be accused of blasphemy. When questioned, Stephen responded with the speech in Acts 7:2-53 in which he summarizes the way Jewish doctrine leads to Christ and how the Jews killed Him like they do all the prophets God sends. (see Luke 20:9-15). Stephen handily refuted not only the original Jews but the council itself. The result?
When they heard these things, they were cut to the heart, and they gnashed on him with their teeth. (Act 7:54)
Then the Jews martyred Stephen for having a vision of the glorified Christ which the Jews rejected since they had already rejected Christ.
So, the source of the wisdom of Stephen? Yes, in the end it is God, but that would be excluded since the Spirit is also mentioned. So it is knowledge of Scripture and the Biblical doctrines contained in it.