The word dynamis is not decorative. Alfred Nobel coined the word "dynamite" in 1867 directly from this Greek root — He chose it because He needed a word that conveyed explosive, concentrated, operative force. That is the direct etymological ancestor of what Jesus promises in verse 8. Not potential. Not latent ability waiting to be activated by the right circumstances. Present, active, explosive force. Romans 8:11: "The Spirit of Him who raised Jesus from the dead dwells in you." The power that exploded death is the power living in you. It does not decrease in force when it distributes itself. It does not need to build up before it can act. It is not dependent on the size of your audience, the sophistication of your presentation, or the receptivity of the room. It is the dynamis of heaven operating through a vessel that said yes.
The geographical sequence of verse 8 is not limited to the first century. Jerusalem is wherever you are right now. Your Jerusalem is your household, your workplace, your city. Judea is your region. Samaria is the people you were raised to avoid. The ends of the earth is what happens when the first three are taken seriously.
Declare It: The Spirit of him who raised Jesus from the dead is alive in me. I carry the dynamis of heaven — the same explosive force that split the upper room at Pentecost, the same power that opened blind eyes and raised the dead in the book of Acts. I am a witness. My Jerusalem is right in front of me. Begin.