“The truth” does not refer to an entity that exists and can be found. But often people speak this way: “The truth is out there. All we have to do is to look for it.”
“The truth” by itself is vague and not very meaningful; it has to be completed by what that truth is about; e.g. the truth about human existence, or the truth about Church history, etc. (…and even then it remains problematic and vague.)