This suggests that Satan thought what Jesus was about to do might be illegitimate, that is, judging him “before the [due] time” (Matt. 8:29). Even the devils believe and tremble (fear) before God. “Thou believest that there is one God; thou doest well: the devils also believe, and tremble” (James 2:19). Of the 2,000 demons in the man, one (Legion) was like the prince of demons, the spokesman.
Verse 7 proves the fallen angels knew Jesus—that he was not an ordinary man. They knew of his preexistence as the Logos and of his close relationship with God. They worshipped him (verse 6) out of fear of what he might do to punish or judge them.