After Pharaoh's people, the next in historical order are the Israelites and those people who adopted the Jewish religion or Christianity. In their case, there can obviously be no question about their either not acknowledging the existence of God or not believing in His being the Ilah and the Rabb. The Qur'an itself affirms their belief in Him on the point and the question which therefore arises is of the particular error for which they were characterized in the Qur'an as "those who went astray". (Quran 1:7)
A brief answer is:
Say (O' Muhammed): "O' people of the Book: Do not exaggerate concerning your faith, and adopt not the wrong notions of those who have gone astray before you, who misled many others, and themselves too strayed from the straight path." (Quran 5:77)
From this, one may conclude that, in essence, the Jews and Christians too were guilty of the same error into which others had fallen earlier, and that in their case this arose out of exaggerated piety. Let us go into the matter in some detail, with the help of the Qur'an:
(i) And the Jews said: "Uzair (Ezra) is son of God, while the Christians said, "Isa (Jesus) is son of God." (Quran 9:30)
(ii) It was kufr on the part of Christians, to say that God was the same as Jesus son of Mary; though Jesus had himself said, for a fact, "O' sons of Israel, give your 'ibadah to Allah. Who is also your Rabb and my Rabb." (Quran 5:72)
(iii) Verily those who said 'that God is one of three, committed kufr, for there is but one Ilah and there is no ilah but He. (Quran 5:73)
(iv) And there will come a time (the Day of Judgment) when God will ask "O' Jesus, son of Mary, did you tell people to take you and your mother as ilahs besides Myself?" to which Jesus will reply, "Glory be to you! How could I have dared say that which I had no right to utter!" (Quran 5:116)
(v) It is not for any person that, after being given the Book, and being endowed with hikmah [Literally, this word means wisdom; but when used in reference to a Prophet, it means that special wisdom which comes automatically after investment with the office of Prophethood, and which enables the Prophet to understand and expound the implications, and requirements of the Divine Injunctions. A. A. Maududi] and invested with Prophethood, he should go about telling people to give up God and instead give their allegiance and 'ibadah to him. Far more fitting it is that he should say: "Believe firmly in Allah as the Rabb (in every sense of the word), as you find it written in His Book, and as you learn of yourselves and teach others." Nor, again, is it for a prophet to tell the people to regard the angels and the prophets as rabbs. Would he enjoin kufr to you after you have become Muslims? (Quran 3:79-80)
What we learn from the relevant verses is that the first error of the Jews and Christians was to raise their Prophets, and saints, and the angel, etc., to the status of divinity out of exaggerated regard for them, to believe them to have a say in the ordering of the universe and its affairs, to worship and address their prayers to them, treat them as partners in rububiyyah and in godhood in the supernatural sense, and to believe that they could remit their sins and come to their rescue and protect them from misfortune and disasters.
Their second error lay in their making even their scribes and hermits into rabbs, besides God (cf.9:31). In other words, the people whose real function was to expound God's law to others, and to reform the people morally and spiritually to make their conduct conform to Divine precepts were gradually assigned authority to determine, on their own, what was to be treated as forbidden and what as permitted, without reference to what was said in the Book. They could forbid any practices they did not approve, and institute any others they fancied. And in this way both Jews and Christians fell into the same two basic errors as that into which the people of Prophets Nuh and Ibrahim (on whom both be peace), the 'Aadites and the Thamud and the people of Madyan and others had fallen earlier. Like them, they too made the angels and their religious leaders to be partners with God in Rububiyyah in the supernatural sense, and in moral, cultural and political spheres too. And so they began to take their cultural, economic, moral and political principles from human beings, disregarding the Divine injunctions, until they reached a stage about which the Qur'an says:
Have you noticed the people who were given a portion of the Book of God, but who (instead of making it the basis for their conduct), believed in jibt and taghoot? (Quran 4:51)
Say (O' Muhammad): "Shall I tell you who are worse as to their ultimate fate with Allah than even the fasiqs [A fasiq, according to the Qur'an is one who breaks his covenant with Allah, who severs the ties between Him and His creatures and between man and man, and who creates mischief upon earth (cf. note in Tafhim-ul-Qur'an. Vol.1. p.61. relative to 2-27-2). A. A. Maududi]. It is those who drew the curse of God upon them, those who invited His wrath, and of whom many were turned into apes and swine by His Command, and who gave their worship to taghoot; they are the lowest in degree, and the farthest astray from the straight path." (Quran 5:60)
The word jibt is a comprehensive term for all myths and superstitions, embracing such superstitious things as magic, the art of the occult, black magic, necromancy, witch-craft, soothsaying, divination, the belief in talismans or lucky stones or unlucky colors or numbers or natural phenomena, etc., or in the influence of the heavenly bodies on human affairs. As for taghoot, this term applies to every person, or group of persons, or organization or institution which, instead of submitting to God and His Injunctions, rebels against them and virtually sets up himself or itself as god instead, or is so set up by people. So when the Jews and Christians committed the two errors indicated above, the result of the first was that different kinds of superstitious beliefs took hold of their minds and of the second that their scribes and hermits, etc., gradually came to assume the same right to tell people what to do and what not as had been presumed by those who were open rebels against God.