“Whenever the unclean spirits
Saw Jesus,
They fell down
Before him.
They cried out.
‘You are the Son of God.’”
καὶ τὰ πνεύματα τὰ ἀκάθαρτα, ὅταν αὐτὸν ἐθεώρουν, προσέπιπτον αὐτῷ καὶ ἔκραζον λέγοντα ὅτι Σὺ εἶ ὁ Υἱὸς τοῦ Θεοῦ.
This is somewhat similar to earlier in Mark, chapter 1:23, when Jesus made the unclean spirit leave the possessed man. Jesus commanded even the unclean spirits, so that they listened or obeyed him. He seemed to have some special spiritual powers that no one else had ever seen. Here Mark noted that these evil unclean spirits (καὶ τὰ πνεύματα τὰ ἀκάθαρτα) fell down before Jesus or worshipped him (προσέπιπτον αὐτῷ), whenever they saw him (ὅταν αὐτὸν ἐθεώρουν). They cried out or shouted out to Jesus (καὶ ἔκραζον λέγοντα), that he was the Son of God (ὅτι Σὺ εἶ ὁ Υἱὸς τοῦ Θεοῦ), when no one else recognized this. This unclean spirit world was alive and active in first century Israelite culture.
Eugene Finnegan Bible Project 