The first time I personally came to REALLY know that demons are real, was after a long journey of seeking out the truth about the spiritual realm, in a variety of occult practices.
You may not know me, but I know everything about you. Psalm 139:1 I know when you sit down and when you rise up. Psalm 139:2 I am familiar with all your ways. Psalm 139:3 Even the very hairs on your head are numbered. Matthew 10:29-31