Thats a pretty simple question to answer...
Satan has as much power as GOD allows him to have....
His *Influence* on earth, is who we fight against.
Ephesians 6:12
For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms....
So when tornadoes wipe out christian churches, God allowed satan to power to do so, is that it?
Satan has power over the earth, until Christ returns..
Satan has no Power over the Holy Spirit..
Satan cannot stand where GOD does....