I looked it up, and the expression used by St. Alphonsus Liguori in the original Italian was indeed “divina madre”. In Italian it’s a little more clear that the expression means “mother of God, Who is divine” rather than “mother who is divine.”
But if people don’t want to get this, I don’t know how you can make them get it.
Italian gets this use of “divina” from a whole class of Latin expressions. Very often, you get saints called “Divus Johannes” or “Divus Hieronymus” or whatever. Before that, you used to get emperors or various other famous Romans called “Divus” this and that.
The expression meant at root “someone touched by the gods/God”, and hence “someone godlike in some fashion.” It was an expression that even in pagan times was almost always used about dead people only. When the various emperors started to accept divine honors, it began to mean “deified.” But when Christianity took it over, it was changed again to mean “someone in heaven with God,” and became just a fancy way of saying “Saint Somebody.” (And of course, today in Italian, a “diva” is not a goddess or a deified person or a saint, but rather, a really good opera soprano.)
It is entirely possible to find an early Christian (like St. Jerome) ranting about pagan gods and polytheism being bad, and then quoting “Divus Matthaeus” or one of the other Gospel writers. Are you going to let this sort of thing shock you, or are you going to figure out what’s being said and read it the way the author meant it?
So the real question is whether normal Christian readers are capable of reading normal Christian prose from other times and places in a sympathetic way, or whether we are going to demand that all Christian writings (and the Holy Bible) be written only in a way that seems normal to 21st century Americans.