He comes out with his deceitful ignorance to say things which every sane will sense to be absurd. He talks about the Holy Qur'an 14:4 where Allah says:
"We sent not a messenger except (to teach) in the language of his people, in order to make (things) clear to them. Now Allah leaves straying those whom He pleases and guides whom He pleases: and He is Exalted in power, full of Wisdom." (Qur'an 14:4)
He comes up with the argument that;
'the message needs to be delivered in the language of the people to whom the messenger is sent, not the language of the people the messenger belongs to.'He is giving the impression as if the Qur'an uses the word 'his people' only to mean the very own tribe and the kinsmen of the Prophet and not the people to whom he is sent.
This is a misrepresentation and by the way of it he is only trying to make the ground plain for his further twisting, for the very next part of the same verse clarifies the whole thing when it says that Allah does it so ', in order to make (things) clear to them.' Thus clarifying that by the words 'his people' Qur'an refers to all the people to whom a Prophet is sent whether they are of his own tribe or not. The famous commentator of the Holy Qur'an Al-Raazi in his commentary to this verse writes:
"It is not correct (to say) that the words 'his people' refer (only) to the people of his city (or tribe etc.);"(Tafseer Al-Raazi (Mafatihul Ghayb) 9/206 under Qur'an 14:4)
Katz in his, what he calls, 'side remark' takes much trouble to show us his mental caliber when he writes;
'A messenger is not sent with a language, but with a message (that is formulated) in a certain language.'This clearly shows that he needs to take some simple language classes, a person who cannot simply understand the plain words; he is surely bound to fail to understand the eloquent Qur'an. Anyone with even a little literary taste knows that the 'correction' which Katz so proudly has comes up with is in fact the very obvious meaning so easily understood.
The case of Prophet Muhammad (PBUH):
Now we come to the case of Holy Prophet Muhammad (PBUH) in context of the present discussion. No doubt as Qur'an says, Holy Prophet (PBUH) was sent for the whole humanity i.e. his message is for the whole humanity and for all times till the End of Times. Qur'an says:
Say: "O men! I am sent unto you all, as the Messenger of Allah." (Qur'an 7:158)
But we know that he spoke only Arabic and the Qur'an also is in Arabic while the people of the world speak hundreds of different languages. So, is this a contradiction with the above quoted verse 14:4 of the Holy Qur'an? Actually it is not!
Here we need to see that unlike all the earlier prophets it was Prophet Muhammad (PBUH) alone who was sent to the whole humanity as reported in the Hadith which Katz also quoted. Now, there were are only two ways, either Qur'an should have been revealed in all the various languages of the world, in that case it would have been tragedy as many people would misunderstand the message and many more likes of Katz would get the chance to play with the fire. Or the other way was, as actually happened, to reveal the Qur'an in only one language (i.e. Arabic) and then let the translations and commentaries of the Qur'an to reach every nook and corner of the Earth, along with the knowledge of the Arabic language.
As the immediate listeners and all the people with whom the Holy Prophet interacted in his life time knew and understood Arabic so the Holy Prophet (PBUH) was sent with the message in Arabic language. There is much wisdom in Holy Prophet's being raised in Arabia as it was right in the center of all the major civilizations of the world and on their mutual trade routes and Arabic language happens to be the only language that has not undergone any considerable change at least in its written form. While all the other languages have undergone prodigious changes, many even have died out.
Holy Prophet's mission was to deliver the Message to humanity and explain the Holy Qur'an. As to the da'wah work, the whole Ummah shares it. Allah says in the Holy Qur'an:
"Say thou: 'This is my way: I do invite unto Allah,- on evidence clear as the seeing with one's eyes,- I and whoever follows me.'" (Qur'an 12:108)
The Holy Prophet did not personally interact with non-Arabic speaking people but he directed and inspired his companions to take the Message of Islam to all parts of the world which they did to their best. And while Holy Prophet (PBUH) directed his companions to go to all the nations, he directed them to learn their languages as well. He directed Zaid bin Harith to learn Hebrew and asked Salman Farsi (the Persian) to teach others the Persian language and so on. His companions did learn other languages and then spread the message of Islam.
And yet another thing I would like to mention, though generally Qur'an uses the word Messenger only for the Prophets but it also uses it for others including the preachers who do not enjoy the status of Prophethood as we see in Qur'an Surah 36. Allah says:
"Set forth to them, by way of a parable, the (story of) the Companions of the City. Behold!, there came messengers to it." (Qur'an 36:13)
According to Ibn Abbas, Qatadah, Ka'ab Ahbar, Wahab bin Manbah they were some preachers, followers of the True Faith and lived sometimes between Prophet Jesus (PBUH) and Prophet Muhammad (PBUH). Ref. Tabari, Baydhawi, Ibn Kathir, Al-Raazi etc.
So we see there is no contradiction, the Holy Prophet (PBUH) was sent to the whole humanity, the language of those who directly interacted with him, he knew and the language of the rest he told his companions and followers (who may also be termed as 'messengers' as per Qur'an 36:13) to learn and spread the Message around the globe.
"And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues;" (Mark 16:17)
It’s a challenge to all the Hot-Gospellers and Bible-Thumpers if they can speak foreign languages for their Book of Authority comes up with this as an acid test for their belief.
INDEED ALLAH KNOWS THE BEST!