If a Muslim says
    the name of Allaah over the meat of the People of the Book, does this mean that it is
    permissible for him to eat it?
Question

                I very doubtfull about the fact that many
      muslims say that if a christian or a jew give you meat to eat, we must say basmala to make
      it halal. But the islam teaches us that what is haraam is still haraam, even there is a
      good intention (i.e. to say basmala)
Praise be to Allah.The scholars agree unanimously that it is permissible to
    eat the meat of the People of the Book, Jews and Christians, if the name of Allaah is
    mentioned at the time of slaughter, as Allaah says (interpretation of the meaning): “Eat
    not of that (meat) on which Allaah’s Name has not been pronounced (at the time of
    slaughtering of the animal)…” [al-An’aam 6:121]. If the person
    mentioned a name other than that of Allaah, such as the name of ‘Uzayr or of the
    Messiah, then it is not permissible to eat of it, because of the general meaning of the
    aayah (interpretation of the meaning): “He has forbidden you… that which is
    slaughtered as a sacrifice for others than Allaah.” [al-Baqarah 2:173]. 
It is also a condition that the meat should be slaughtered in the
    manner prescribed by sharee’ah. If it is known that the slaughter was not done in the
    proper Islamic manner, e.g., by strangulation or electric shock and so on, then it is
    haraam.
As for the claim that some make, that it is enough merely to mention
    the name of Allaah when eating, this was reported regarding some Muslims who were new in
    Islam. The Sahaabah (may Allaah be pleased with them) asked the Prophet 
 (peace and
    blessings of Allaah be upon him) about this, saying, “O Messenger of Allaah, some
    people who are new in Islam brought us some meat, and we do not know whether they
    mentioned the name of Allaah over it or not.” The Prophet 
 (peace and blessings of
    Allaah be upon him) said: “Say the name of Allaah over it and eat it.” (Reported
    by al-Bukhaari). The command should be understood as meaning that one
    should be on the safe side, provided that one does not know beforehand that the meat is
    not slaughtered properly. And Allaah knows best.