This is undeniable definite evidence of the demonic.
The devil appeared to a very humble monk as an angel of light and told him, in order to pull him down into arrogance: "I am Gabriel and I came to salute you, for you have many virtues and are worthy.""Look, you must have made a mistake," the humble monk answered, without losing his composure. "I am still living in sin, and for this reason I am not worthy to see angels."
• To learn to discern false visions from true, read lives of saints for more examples of true heavenly visitations. And for specific information on the charismatic demons, read Orthodoxy and the Religion of the Future by Fr. Seraphim Rose. Also, read Soul After Death which discusses the now popular near-death experiences and out-of-body experiences.