The Roman Catholic Church teaches that we are obligated to believe in the Bible revelations and miracles but not in the revelations or miracles approved by the Church since. The latter such as the apparitions of Lourdes are optional. The Bible miracles and revelations are examples of public revelation. Lourdes is an example of private revelation.
The Church is clear that there is no new revelation from God needed since the last time one of the twelve apostles gave the word of God.  The Bible itself says that all truth has been given in Jesus.
“Throughout the ages, there have been so-called ‘private’ revelations, some of which have been recognized by the authority of the Church. They do not belong, however, to the deposit of faith. It is not their role to improve or complete Christ’s definitive Revelation…. The Christian faith cannot accept ‘revelations’ that claim to surpass or correct the Revelation of which Christ is the fulfilment, as is the case in certain non-Christian religions and also in certain recent sects which base themselves on such ‘revelations’.” (CCC 67).
This makes no sense. It is like saying you can believe the doctor on Thursday but you don’t have to believe what he says on a Friday.

It is though that lots of different groups report miracles or supernatural events and that they have no problem finding the academics and scientists to authenticate them. If so, then why should we believe in the Catholic Church just because a few eminent doctors say that miracles have happened and ignore say the Christian Science movement which reports miraculous mind cures verified by very intelligent and reliable people?
Religion stresses the miracles of the past when the ones of the present and the future should have more weight because they have been examined by more knowledgeable people and tested by our good scientific developments. To believe that a woman has been cured at Knock this year according to doctors is better than to believe that Jesus rose from the dead two thousand years ago. That is why the Catholic Church which claims the best verified extra-biblical miracles cannot make sense when it says we do not have to believe in these miracles but have to believe in the miracles spoken of in the Old and New Testaments.
The Church has to make belief in the extra-biblicals optional for it stakes its infallibility on the claim that what the apostles taught cannot be added to. It is certain however that modern miracles refute that claim though the miracles often deny it for a modern miracle is more convincing than anything just scribbled in some old papyrus two thousand years ago.