{Devils} (daimonia). Demons it should be translated
always. {Suffered not} (ouk (8870)hien). Would not allow, imperfect
tense of continued refusal. The reason given is "because they
knew him" (hoti (8869)deisan auton). Whether "to be Christ"
(Christon einai) is genuine or not, that is the meaning and is
a direct reference to  1:24  when in the synagogue the demon
recognized and addressed Jesus as the Holy One of God. Testimony
from such a source was not calculated to help the cause of Christ
with the people. He had told the other demon to be silent. See on
烘t 8:29| for discussion of the word demon.