The Holy Spirit is the paracletos, the one who comes alongside to advocate and help.
The Holy Spirit speaks to people (Acts 13:22)
The Holy Spirit directs people (Acts 16:6)
The Holy Spirit testifies (Acts 20:22-22)
The Holy Spirit brings hope (Rom 15:13)
The sermon had the fundamentals of the Pentecostal teachings in the Holy Spirit. Nothing new or remarkable there. It made the assumption that the believer would recognise when an inner voice is genuinely divine and when it isn't.
I'm especially interested in this because it was a central thematic question of my masters thesis. I compared Abraham's call to sacrifice Isaac against the claim by Christopher Lee McCuin who killed and cooked his girlfriend because God told him to. Being able to hear the authentic voice of God is crucial. Paul claimed his teaching was a divine revelation (Gal 1:11-12).
Hearing God is good. Recognising it as authentic is hard.