Evil distortions, does evil exist? 

The devil confuses mystics too, impersonating Jesus and Mary, as when Mary gives baby Jesus to Saint Faustina and a distorted apparition shows up instead. All these mystics have written as best as they could about what they saw and experienced. Some of these visions are probably distorted by evil (more intelligent than people), but we can discern with a loving heart what parts belong to God. They may cause us confusion when reading different mystics. For example, Mary passed away, according to the visions of Anne Emmerich, in Ephesus, Turkey; Mary of Agreda says Mary passed away in Jerusalem. I believe Mary of Agreda's account, as Ephesus, according to Saint Paul in the New Testament, was in a state of idolatrous disarray. Mary's age at death is different for sister Menendez, Mary of Agreda, and Anne Emmerich. However, Mary of Agreda is, in my opinion, the most truthful to Jesus Christ's life; I found no single statement against the Gospels. Blessed Emmerich has a few statements that dent its validity, such as: "as people sin, they get darker skin," or when Jesus went back to houses where Mary was denied entry (while fleeing to Egypt) and Jesus would tell their owners that they had no salvation (Jesus would never deny a person after repentance). I like Sister Menendez's prayers and loving discourse with Jesus. Anne Emmerich's visions provide different church dates and other peculiarities, but still, her account has truthfulness, and it has helped me to understand the Gospels based on Jesus' three-year ministry. It is up to the reader to have different sources and the truth will find its way as Jesus and God are pure love and unconditional. It is up to us to be open to that love and realise that anything deviating from it is very likely from the evil one. Also, remember that satan has higher intelligence, but he cannot read human minds, and it is only by our actions that he tempts.

Book: An Exorcist Explains the Demonic: The Antics of Satan and His Army of Fallen Angels by Father Gabriele Amorth

Book: An Exorcist Tells His Story by Fr. Gabriele Amorth

Pope Francis will not accept Medjugorje's Marian apparitions in Bosnia. The messages are 98% correct; it is the 2% placed in clever ways by false apparitions that can confuse people. It is best to wait for Catholic approval by the Vatican. "My heart will triumph" is a beautiful book about Medjugorje to increase our faith. Mary said in the book: "There is only one faith". Messages are of hope, but still, Medjugorje is not approved as a few messages (not in the book) have raised flags. It is the same in Dozule, France (1972). As Jesus' messages are very similar to those of Saint Faustina's, he asked to build a 738-meter cross. Evil apparitions worked extra time to create confusion during these messages and afterward, rendering the apparition non-approved by the Vatican. Counterfeiting is the specialty of the devil, especially around holy places. It weakens faith, which was its intended purpose.

Book: My Heart Will Triumph by Soldo, Mirjana

Archbishop Fulton Sheen better explains the devil,

Having said this, during a eucharistic adoration, I mentally asked Mary why my temptations kept me from properly praying to her, whom I love. A minute later, a random person came straight to me with the most beautiful picture of Mother Mary from Medjugorje and told me to keep it (it had been blessed there on his 10th trip there). It is just beautiful how Mary is connected to us. I had a similar situation in Pisa, Italy. She answers us in the sweetest way. God bless our Queen Mother Mary! She listens to our innermost prayers. This random person had the urge to go to Medjugorje during the Bosnia War (first approved apparitions). There he saw, with other pilgrims, Mother Mary appearing over the tabernacle during adoration, with arms extended. Archbishop Fulton Sheen better explains how close Mary is to us in everyday life and the reason demons fear Mary,

My advice is to follow the Roman Catholic teachings and read the mystics and religious books. Any comments that do not agree with those teachings I mentally discard. Any comments that provide more details and understanding of the Holy Gospels, the Passion of Christ, I incorporate as religious knowledge. For example, many mystics see the Lord crucified, but only Anne Emmerich describes the cross as Y-shaped. Given that these details were not mentioned by other mystics, I would choose to ignore them as I continue reading. Only by reading several different mystics does an ultimate truth seep through that complements the Gospels in the most beautiful way. I take Mary of Agreda's life of Mary as the most correct and a wealth of information; coincidentally, it is the most Church-approved work outside the Bible; sadly, most Christians do not know of its existence.

I know of a person trying to get out of witchcraft, but demons would appear on trees and utility poles, following and taunting him. Only Mary can rescue that person, of weak faith, at that point.

Saint Augustine (420ac) said about polytheism, 

Those who engage in those polluted rites of purification, with their blasphemous ceremonies have some marvellously beautiful visions, whether of angels or of gods, after the supposed purification. ...the devil longs to ensnare men's wretched souls in the fraudulent ceremonies of all those false gods, and to seduce them from the true worship of the true God, by whom alone they are purified and healed. ...'Evil' is merely a name for the privation of good. ...God [in time] turns evil choices to good use.   

Book: City of God by Augustine of Hippo  

But let an exorcist summarize the above and explain the reason for the existence of hell,

The desperation of people, when demons get too close, is better described by some rock lyrics in the 90's. Notice in them how Jesus is cursed, but Mary is not. Let's describe demons by them:

Sober ... Song by Tool : There's a shadow[demon] just behind me. Shrouding every step I[human] take. [demons]Making every promise empty. [demons]Pointing every finger[judgement] at me.[demons]Waiting like a stalking butler. Who upon the finger rests. Murder now the path of must we[demons]. Just because the son[Jesus] has come.Jesus, won't you fucking whistle. Something but the past and done? Jesus, won't you fucking whistle. Something but the past and done?Why can't we not be sober? Just want to start this over. And why can't we drink forever? I just want to start this over.Why? I[demonised person] am just a worthless liar. I am just an imbecile. I will only complicate you. Trust in me[demon] and fall as well. I will find a center in you. I will chew it up and leave. I will work to elevate you. Just enough to bring you down.Mother Mary, won't you whisper? Something but what's past and done. Mother Mary, won't you whisper? Something but the past and done.[demon]Trust me. Trust me. Trust me. Trust me. Trust me.Why can't we not be sober? I just want to start things over. And why can't we sleep forever? I just want to start this over.Why? I want what I want. I want what I want. I want what I want. I want what I want.
Firestarter ... Song by The Prodigy: I[demon]'m the trouble starter, punkin' instigator. I[demon]'m the fear addicted, a danger illustrated. I'm a firestarter, twisted firestarter. You're a firestarter, twisted firestarter. I'm a firestarter, twisted firestarter.I'm the bitch you hated, filth infatuated, yeah. I'm the pain you tasted, fell intoxicated. I'm a firestarter, twisted firestarter. You're the firestarter, twisted firestarter.I'm the self inflicted, mind detonator, yeah. I'm the one infected, twisted animator. I'm a firestarter, twisted firestarter. You're the firestarter, twisted firestarter. I'm a firestarter, twisted firestarter starter.