I feel kind of bad about admitting it, but I have significant doubts about stuff like Eucharistic hosts that literally turn into human flesh with DNA and/or blood.
Oddly enough, I am a strong believer in the real presence of Christ in the Eucharist. A lot of these miracles just seem hard to swallow for me (That isn't meant to be a pun, but on that note I do hope these are just kept on display and no one tries to consume them like regular consecrated hosts and consecrated wine- and I don't think they do try. I've never heard of anyone consuming them that way, at least.).
Anyway, as far as I know even the most stringent conservative interpretations of the rules don't require Catholics to believe this stuff. Transubstantiation, yes, a specific miracle of this nature, no. Vatican investigations just look into whether something is "worthy of belief" or not, rather than deeming them mandatory parts of the faith. So, I'm on okay ground having my doubts there, even though I feel a little odd about it.
Similarly, I don't tend to believe in Marian apparitions, where the Church similarly doesn't mandate belief, but rather looks into whether something is worthy of belief or not, or an obvious fraud or inconsistent with the Catholic faith messaging wise or whatever.
Now, of course, one of the things about this kind of stuff is that we do kind of have to accept that some people involved in this have been named Saints, have parishes named after them, etc.. And of course Popes, including our beloved Pope Francis, seem to believe. I think the Pope is actually in Fatima right now.
I guess one big warning sign for me is that many apparitions of Mary don't seem to match her biblical character. I like her in the bible, I have difficulty identifying with the way she is said to act in apparations. Sometimes it seems like they take her from this shy gentle loving but loyal and brave Jewish girl and woman into something a little closer to a wrathful God type (Don't take that too literally, just a very loose metaphor that wouldn't hold up to too much scrutiny) who is really into scaring people about hell and who has very definite opinions on the Soviet Union.
I suppose people can change in a couple thousand years, its just not something I closely identify with.
I like the rosary, but not the Fatima prayer (Which is still an optional addition, though I've found most groups use it).
Anyway, I do appreciate that these things have kind of become cultural touchstones for Catholics, and part of urban legend. I feel positively predisposed to them when I just stick to thinking about them on that level. The Miracle of the Sun and such is a good story. The only qualm I have at all there, when I just look at it as culture rather than something literal, is whether it is yanking us back towards a stronger concept of hell, when I would like to see us move beyond it into having a stronger concept of grace (But I'm a universalist [small u, not the religious group]- I believe everyone eventually winds up in heaven- or would like to believe that, anyway- so I would tend to say that.
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I'm certainly not knocking anyone for believing in these Eucharistic miracles or Marian apparitions, though. Who knows, you may be right. I'm not perfect. I get things wrong sometimes. Its definitely something a lot of people I admire believe, and certainly allowable and even encourged by the Church. I'm glad that they are sticking to saying that the belief in these individual things are optional, though.
My confirmation Saint was Thomas the Apostle- who doubted news of Christ's resurection until he could feel the marks left from the crucifixion and the spear with his own hands on the risen Christ. As it turns out, the bishop didn't read the name aloud, but I picked one anyway. I'm counting it.