Actually “for all” had
“Pro multis” can be legitimately translated as “for all.” Here is a good explanation:
"At first glance, the official Latin “pro multis” would seem to require “for many.” However,in addition to the fact that the translation “for all” is compatible with Christian doctrine, there is
also a linguistic rationale for it. In examining the fifth chapter of St. Paul’s Letter to the Romans.
For example, we find the following: "For if many died through one man’s trespass, much more have the grace of God and
the free gift in the grace of that one man Jesus Christ abounded for many "(Rom. 5:15).
It is necessary, however, to read the first half of this scriptural passage more carefully. St. Paul says that “many died through one man’s trespass.” Now, unless “many” here can actually be translated as “all men,” this phrase from St. Paul would actually constitute a formal denial of the Church’s dogma,
defined by the Council of Trent, that the original sin of Adam and its consequences were in fact transmitted to all men rather than just to “many!”
But an inspired—and therefore inerrant—letter of St. Paul would be the last place wherewe would expect to find denials of defined Catholic dogma. Indeed the Council of Trent used
a passage from Romans 5 in its definition on original sin! (Decree on Original Sin, no. 2)
Thus the phrase “for many” must be susceptible to more than one interpretation. And in Romans 5:12-13, St. Paul, introducing his discussion of the effects of Adam’s sin, actually employs the
phrase “all men” as a synonym for “many,” which, as noted earlier, he uses a few verses later in Romans 5:15. So even the inspired Apostle to the Gentiles himself demonstrates that it is possible to use the two phrases interchangeably."
-The Pope, The Council and The Mass, by Likoudis and Whitehead
