Could a saint say something wrong about the faith? Also, I’m not sure if this is the right place to out but I have no idea where else to put it.
You’re in the right place.
Saints (and even Doctors of the Church) have been wrong, theologically (we’re talking about matters that had not yet been taught as doctrine during their lifetimes). The greatest Doctor of the Church, for example, St. Thomas Aquinas, had a real problem with the idea of the Immaculate Conception. St. Cyprian of Carthage had a real problem with the validity of heretical Baptism.
Saints are a valuable resource for the Church, but they are not part of the Church Magesterium (teaching authority) and their writings hold no doctrinal status. Saints were not individually protected from teaching error (as is the Church), so sometimes they got it wrong.
Also, if a saint inadvertently teaches something wrong, and then he finds out that the Church has ruled the other way, he will accept the Church’s teaching over his own.
That said, there’s nothing wrong with arguing hard up until the last moment! A lot of saints have!
For example, St. John Newman. Didn’t like the definition of papal infallibility. Didn’t like the definition of the Immaculate Conception. Swallowed his pride and let the Church be his guide.
If you ever see a theologian saying, “I submit all this to the judgment of the Church,” that’s what they’re doing ahead of time - saying they’re prepared to be found wrong.
Do you mean Blessed John Henry Newman or St. John Neumann?
If the former, I’d love to see where in his writings he stated those opinions, especially regarding the Immaculate Conception.
Surely he means Bl. (not St.) John Henry Newman. Newman’s opposition to this teaching is well known.
He is in good company, with the Angelic Doctor, St. Thomas Aquinas.