This is of course only my opinion, but might it be the pope did not release the third secret because he just could not believe that God would allow this to happen to His Church in that way. Therefore he no doubt could not believe it was a true message from heaven.
"The good continue on their way but without paying attention to the Message ... I cannot give any other details, since it is still a secret ... Only the Holy Father and His Excellency the Bishop of Fatima would be able to know it in accordance to the Will of the Blessed Virgin ... But they haven't willed to know it as they did not want to be influenced."
Pope Pius XII, therefore, without a doubt, preferred to wait for 1960, but he died before then. What a loss for the Church!4
http://www.fatima.org/crusader/crthird/sfrpg05.asp I would also reccomend reading Fatima in Twilight by Mark Fellows. We can only speculate about the motives of anyone but the humanistc way of thinking is that "We can't realease the message. It is too much for them to handle." Or, "I or the next valid Pope will release it in 1960 when it will be more understood and cause the least amount of scandal".
Even now, 50 years later, with all the results before us, the mere possibility of SV or a false pope approving a false council causes
great scandal to some. Even the idea that not all Popes were perfect causes
great scandal to some. Knowing how many lay people react to such things could scare some people from presenting the hard facts. But our Lady thought we would be ready for it, at least by 1960 and I tend to side with her. :smile: