You misunderstand Catholic teaching. The keys do not give the Pope authority over heaven. Instead they are an assurance that whatever official decisions he makes will be in-line with heaven because the Church is being guided by the Holy Spirit of God. If the Holy Spirit guides the Church in a manner that displeases God, then means that either the Holy Spirit of God guided him incorrectly or Jesus lied and the Holy Spirit is not guiding the Church in all truths.
Either option shakes the very foundation of the faith.
Incorrect again. Church disciplinary decisions do not always have to please God, they have varying levels of authority. Even in their highest levels of authority they are subject to imperfection, or while being binding, and nevertheless not the best decision and ultimately not pleasing to God, despite not being directly sinful (i.e. ordering sin) and binding.
You can read the Catholic Encyclopedia on this to verify it if you like.
In this case we are talking about two things. Removing the discipline of celibacy – this is a removal, in other words, it is not legislating sin directly, merely removing a restriction. This can quite easily be displeasing to God, but still not violate direct moral law. Because people are still free to choose celibacy or not.
Fatima. Fatima is a private revelation. The Church can judge whether any of its contents are against the Faith (they are not, this has been declared). She can judge whether it is worthy of believe. She has decided so. She cannot judge whether conditions that depend upon the judgement of Heaven have or have not been fulfilled. Popes and prelates can issue documents about how -they think- these things have been fulfilled, but that doesn’t mean that they are, that this makes the Church fallible in some way, etc. They aren’t intending to issue anything with the infallible authority you want to put into it, because it doesn’t apply here and they certainly wouldn’t think of it.
Anymore than if the Pope made a declaration on a mathematical problem it would be an issue or not. Except if some one came along and said, “The Pope just made an infallible declaration on mathematics!” and caused trouble. In some things authority applies, in some things it doesn’t. In some things there are some protections, in others there aren’t. And one shouldn’t overrate or overextend the protections.
The Church has issued many breviaries and Bibles in the past. There have been errors in them. Official books. The breviary the priest has to pray every day. The Bible, well… it’s the Bible!
Every order the Pope gives his bishops and prelates on how to handle Church discipline and day to day matters, is not the perfect, best, always pleasing to God advice it could be. All his actions aren’t either.
What you need to do is get a clear idea of what authority is, when it is fallible, when it is infallible, and what levels of it there are, and what the limitations are as well as where the perfections are. You should study up.
You want to prove what I’ve said wrong? Cite sources and site them directly on target, don’t overextend what they are saying. And look at Church history and the many revelations the Church has given her imprimatur to being distributed…
Like the above I have just cited.

Obviously if St. Catherine of Siena can tell the Pope he’s sinning by not enforcing Church discipline… and the Pope doesn’t condemn her for it on doctrinal grounds, despite not listening well enough – the principle is established. The Pope can screw up on discipline. Ditto St. Bridget of Sweden.
I am unclear as to the full realm of possibilities of how bad things can go in certain areas myself. But I am clear that they can go bad to some degree, and I think especially by omission and imperfection.
Just because something isn’t directly a moral evil, doesn’t mean in Heaven God approves of it. I.E. tomorrow, I may go to the store, buy some apples, and give them to the poor. But God wanted me to go to the park, buy some crackers, and feed the pigeons. He gave me the grace to know this, I denied it. Sin. No absolute moral law about crackers and apples. Yes God in Heaven wanting me to do one thing, I in my humanity do another.
The Pope can legislate something not intrinsically evil directly in the moral or natural law but still not what God wants. Depending on the authority and area of the legislation it can be evil no doubt, i.e. when a corrupt Pope for example, consecrates a corrupt bishop. We are bound by the legislation as long as it isn’t clearly morally evil, but that doesn’t mean up in Heaven some scales aren’t being weighed and it’s the right decision overall.
I don’t know how to sort it all out but I don’t think any of what I have said above is mistaken. There’s more to certain areas of it certainly.
If I am wrong, I submit to the Church’s correction. I too am a learning Catholic. I encourage people to learn one way or another and find the sources, don’t rely on me at all. Go ahead and prove it if you like, I would love to learn so, because whoever learns the truth always ‘wins’… though I am not in this to win… I prefer to lose when I am mistaken… the truth should be clear… it’s horrible to be in error on one single emphasis… and especially to do so and promote it… I got into this thread in sympathy for the way some people who know Fatima very well are treated like lepers, as if in fact, they were pro-abortion or something… actually I think such people sometimes get treated more kindly.
