My favorite comeback to this is one I heard many years ago from one of the local guides, and it is: "Then satan has converted!". Scripture tells us that you will know by their fruits. And the fruits of Medjugorje are amazing. Over 30 million people have visited Medjugorje since the apparitions began in 1981. I have personally witnessed countless dramatic healings of mind, body, and spirit there over the years. I have been in a parish office in Medjugorje where there are volumes of medically documented healings. I have seen countless conversions to a deeper Catholic Faith, conversions to the Catholic Faith, or simply conversions back to God. Take a look at who is involved with Adoration of the Blessed Sacrament at church, who is involved with prayer groups, attends daily Mass, is on fire with their faith. It is many times someone who has been to Medjugorje. This new breath of life is the grace that is extended to everyone who asks. Our Lady has repeatedly said that "This is a time of grace." We must take advantage of it!
The message of Our Lady in Medjugorje is pray every day, fast on bread and water on Wednesdays and Fridays, read the bible every day, go to monthly confession, and attend Holy Mass as often as possible. How could one conclude that this is the work of satan?
One can refer to Scripture once again when we look at Matthew 12:24:
"But when the Pharisees heard this, they said, "This man drives out demons only by the power of Beelzebul, the prince of demons." But he knew what they were thinking and said to them, "Every kingdom divided against itself will be laid waste, and no town or house divided against itself will stand. And if Satan drives out Satan, he is divided against himself; how, then, will his kingdom stand?"