This notion of the Holy Spirit guiding the Church has been the constant teaching of the Church, from the Fathers, Doctors, theologians, etc. Montini is right.
It's a gross generalization that assumes many things, a) the orthodoxy of the pope/cardinals/bishops, b) a love of truth, God, and the Faith, and c) the will to spread the Gospel and save souls. It also assumes the obvious...that heretics didn't enter the Church to prepare for the antichrist.
The fact of the antichrist and how it could happen and what would God allow, has always been a mystery. The antichrist only rules for 3.5 years, with a public life before this of (guessing) 10-20 years. So, round that to 25 years that the antichrist is known and "working".
We all know that this 25 years is unlike ANY period in history, both of the world and of the Church. And for 2,000 years God has not allowed any similar events to occur, until the times of antichrist, which are unprecedented.
The point being, in the grand scheme of the Church, V2 has only been 60-70 years, which is a drop in the bucket of history. If we are leading up to the UTTERLY UNIQUE times of antichrist, how can anyone say "God wouldn't allow x, y or z"? Or, how can anyone say, "Well, this can't happen because it's never happened before?" We KNOW that the end times will be unique. We know that will be unprecedented. To compare our times with prior times is silly and naive.