I had the privilege of meeting Fr Gruner when he came to give a "day of recollection" at a friend's house nearby. He was quietly spoken and very humble. For all the controversies that surrounded him, I happen to believe he was telling the truth. That was my gut feeling anyway.
Just before he died, he went to the Vatican in April of this year on Fatima business, and met with the most senioir living exorcist - Father Gabriele Amorth - now 90. Father Amorth gave him an urgent message.
Father Amorth said that, unless Russia is consecrated as per Our Lady's instructions, by the end of October 2015, the dark prophecies of Fatima may well happen any time after that. One of the prophecies says whole nations will be annihilated if men do not repent.
I think one should take this very seriously - Father Amorth seems to have insight.
Father Amorth is author to various books - here is one example. It is a good read.
So what does one do? If you are a Catholic, make sure you are in a state of grace, and if you haven't taken up the daily rosary - now may be a good time to start! If you are not a Catholic, you can still pray the rosary - as this will lead you to the Truth. There are plenty of web resources on how to pray the Rosary. You can get rosary CDs for the car, or buy a version from the App store. The rosary may be the greatest weapon of all time.
