[Florida man arrested for driving into a church and setting it on fire]
It's possible that the perpetrator may just be suffering from schizophrenia exacerbated by anti-Christian hysteria. It's also impossible to discern over the internet whether or not he's demonically possessed. However, the two conditions aren't mutually exclusive.
Considering that he attacked a parish affiliated with FSSP--a priestly confraternity dedicated to celebrating the Latin Mass--ruling out demonic involvement seems imprudent.
As people convert en masse to a hostile heretical cult while many clergy preach worldly doctrines directly at odds with perennial Magisterial teaching, Satan will only redouble his attacks on Christ's flock.