Do you believe in God?
If you do, that puts you more or less in the same company with Satan and his demons, all Protestants, Muslims, Jews and many others. All of them believe in God; some as much as Satan does. The Devil absolutely believes in God.
St. John the Apostle and Evangelist tells us,
The way we may be sure that we know him is to keep his commandments. Whoever says, “I know him,” but does not keep his commandments is a liar, and the truth is not in him. (1 Jn 2:3-4)