What's the secret? A lot of Catholic saints have predict an apostasy at the end times. The so called reformers tried to call it in 1500's era. An apostate(possessed) person can not truly say the creeds. I know a friend who dabbled in the lies of the new age. She claimed she was Catholic. So I challenged her in many ways to confess Jesus Christ in the creeds. There was demoniac manifestations stopping her from vocalizing the Words.
The creeds have been there for almost 2000 years. I truly believe if an apostasy does happen it will be when the creeds are taken out. And only then.
I was once - long ago - told that the Third Secret contained these prophetic words:
The Antichrist shall arise and become the Head of the Church
No idea whether this person - the Master of a Masonic Lodge, by the way - told the truth, but it is understandable why the Vatican of 1960 - already planning Vatican II and infested with apsotasy - would suppress those words.