I found this description in Wikipedia on infinitive.
As a modifier of a noun or adjective. This may relate to the meaning of the noun or adjective ("a request to see someone"; "keen to get on"), or it may form a type of non-finite relative clause, like in "the man to save us"; "the method to use"; "nice to listen to".
I've got a question about "the man to save us." Why is "to save us" used, not "saving us"? If I said "the man saving us" instead of "the man to save us", would it mean other thing? Thank you.
for example, there are these contexts:
"He must be the man (to save us/saving us) from cruelty."
"He is the man (to save us/saving us) although he's also in a difficult situation."
I created those sentences, so they might be awkward, but please answer which is suitable.
My guess is that in the first sentence, "to save us" is suitable, and in the second, "saving us" is suitable.