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Talking to Jews and Christians
Both Jews and Christians believe in that part of the Bible which Christians call the Old Testament. The Old Testament contains references to the prophet Muhammad, on whom be peace and blessings. That Book declared him to be a true prophet. So it is necessary for the Jew and Christian to believe that Islam is true. You therefore do not need to argue over the details of Islam with a Jew or Christian. If he thinks Islam is wrong on any point he has to answer for himself why his Bible recommends Muhammad if he taught a false religion. If he wants to reject the prophet Muhammad (pbuh) then he has to also reject his Bible. But then if he rejects his Bible he is no longer a Jew or a Christian and you have won the debate.
Now what remains is for us to specify where in the Bible to find mention of our prophet. In the Old Testament there are many references. The most significant is Song of Solomon, chapter 5, verse 16. This verse mentions our prophet by name. It says in the Hebrew language Bibles "He is Muhammad." But English translation have "He is altogether lovely" instead of the real truth. You need to insist that, since it says our prophet's name in the Hebrew, the "altogether lovely" translation is nothing more than a camouflage hiding our prophet's name. Tell every Bible reader whether Jew or Christian to ask any Hebrew scholar to read the Hebrew word which appears as "altogether lovely" in the translation. You will hear that word pronounced "Muhammad." Why then hide what you should believe?
Now the Jew or Christian may feel backed into a corner and attempt to escape by throwing you this punch. They may say that if you refer to the Bible you should believe in everything it says. You should reply that you do not believe in everything the Bible says. And that is alright for you because you never claimed that the Bible is, in its present form, entirely the word of God. On the other hand both the Christian and the Jew say that the Song of Solomon is the word of God. How can they refuse what it says?
The important distinction is as follows. You are asking them to recognise the man whom their Bible speaks about not because you believe in their Bible but because they do. You are simply using a valid form of argument to establish a proof. What they accept as their authority is proof against them, not against you. You are simply turning their proof back on them. What they say is the Word of God is telling them to believe in Muhammad (pbuh). How can they escape this belief?
In sum, no matter what objection they raise against Islam, remember that in reply you can always argue as follows. If there is something wrong with Islam why does the Bible recommend the prophet who taught us this religion? If they cannot answer this then you also do not need to answer their objection.
If all this seems too easy it is just because the truth is on your side. It wins with flying colours. Allah says that when the truth is hurled against falsehood it smashes its core.