The devil can appear as an angel of light. 2 Corinthians 11:14, And no wonder, for even Satan disguises himself as an angel of light. Multiple religions were started when someone had a vision from an angel who disclosed to them new revelations. I don't believe these visions were a figment of their imaginations. I believe they were real and powerful. Satan is real and want's to lead people astray into false doctrines.
The Mary from the apparitions will lead you astray into a false gospel. The real Mary is not Omni-present and can't hear your prayers. She always pointed to Jesus and never herself. Don’t follow these!
I recommend the book Messages from Heaven by Jim Tetlow. He discusses the messages given by Mary in the apparitions and how they do not align with the Bible.
