That is possible but what motive would a “real” Messenger of God have to alter the message? It would seem to me that any so-called messenger who did that would be a fraud, not a Messenger sent by God.
What motive would an honest employee have to steal? Still, stores and banks have cameras over the tills.
Being able to verify means that a person can be above reproach. Which is stronger confirmation that a person is relaying a message faithfully?
- the fact that a messenger has good character, or
- the fact that he has good character AND the fact that he would have had no opportunity to lie.
Our judgement of a person's character can be wrong, so if your trust in the message is based entirely on your judgement of the character of the messenger, the message will always have some level of doubt.
It is true that there is no way they can prove they got a message from God.
So then this creates a barrier to acceptance of the message.
Why do you think God would want barriers to acceptance of his message?
It has never been the “job” of the Messengers of God to spread the message He received from God. It was always the job entrusted to His followers.
That makes the problem worse. Every set of hands the message goes through is another potential point for error to creep in. How much error? There's really no way to tell.
Messengers of God are both human and divine by nature. They are inerrant in the way they receive and reveal messages from God.
... you assume. With no real way to confirm.
Humans who receive the messages might misunderstand or distort the meaning of the message but if the message is clearly written it is unlikely to be misconstrued.
Clearly written... by the messenger, not by God, right?
Translations into different languages can be done carefully so as not to lose the original meaning.
That's impossible. Even with the best translation, nuance is lost: what rhymes or has a certain meter in one language won't have this in another. A pun in one language won't be a pun in another. Idioms vary from culture to culture (and from generation to generation within the same culture).
And translation often requires the translator to infer things that aren't in the original text: if you're translating the sentence "you look happy" into French, do you translate "you" as "tu" or "vous?" Depends on what we assume about the attitude the person speaking has toward the person they're addressing, which may or may not be clear from the text.
Translation is partly a creative endeavor on the part of the translator.
That is where faith comes in. We either believe that the message is from God (thus correct) or not. That is based upon our trust in the Messenger, and that is why it is so important to check Him out carefully before we choose to believe He is a Messenger.
How could you "check him out carefully?"
What set of things about a person could you check that could justify the conclusion "... therefore, we can trust anything that this guy says comes from God?"
There can be no two-way communication from God because God only communicates one way – to the Messenger. The Messenger dos not talk back to God to verify that it was God speaking to Him.
You realize that all you did here is beg the question, right?
It is not about what God is capable of doing; it is about what humans are capable of understanding.
So then it's about what capabilities God is capable of instilling in humans.
There is no way any human could ever understand direct communication from God because no human has that capacity since no human has a divine mind. Thus there is no way for God to communicate with humans without using a Messenger who acts as a “mediator” between God and man. He alone can bridge the gap because He has qualities of both God and man.
So regular humans don't have any way to confirm that a supposed message from God actually came from God?
I understand that concern, but the task that God has entrusted humans with is to
differentiate between the true Messengers of God and the false messengers. Jesus put it very succinctly:
Matthew 7:15-20 Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves. Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. Wherefore by their fruits ye shall know them.
Fruits: the pleasant or successful result of work or actions:
FRUIT | meaning in the Cambridge English Dictionary
So if someone seems good, this is a sign they're a messenger?
Even if - for reasons that you haven't really explained - God can't communicate with "non-messengers" directly, God could still do better than what you suggest he's doing now.
For instance: many messengers. If a thousand - or even a dozen - messengers all lived at the same time, all in total agreement with each other and all supporting what each other says, any one messenger who decided to change the message could be easily spotted. It wouldn't be completely foolproof, but it would address some of the inherent problems with having one messenger at a time.