In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Allaah [The Most High] said:
أَفَرَءَيۡتُمُ ٱللَّـٰتَ وَٱلۡعُزَّىٰ
وَمَنَوٰةَ ٱلثَّالِثَةَ ٱلۡأُخۡرَىٰٓ
أَلَكُمُ ٱلذَّكَرُ وَلَهُ ٱلۡأُنثَىٰ
تِلۡكَ إِذً۬ا قِسۡمَةٌ۬ ضِيزَىٰٓ
إِنۡ هِىَ إِلَّآ أَسۡمَآءٌ۬ سَمَّيۡتُمُوهَآ أَنتُمۡ وَءَابَآؤُكُم مَّآ أَنزَلَ ٱللَّهُ بِہَا مِن سُلۡطَـٰنٍۚ إِن يَتَّبِعُونَ إِلَّا ٱلظَّنَّ وَمَا تَهۡوَى ٱلۡأَنفُسُۖ وَلَقَدۡ جَآءَهُم مِّن رَّبِّہِمُ ٱلۡهُدَىٰٓ
Have you then considered Al-Lat, and Al-‘Uzza (two idols of the pagan Arabs); and Manat (another idol of the pagan Arabs), the other third? Is it for you the males and for Him the females? That indeed is a division most unfair! They [i.e. these idols and objects you worship besides Allaah] are but names which you have named, you and your fathers, for which Allah has sent down no authority. They follow but a guess and that which they themselves desire, whereas there has surely come to them the Guidance from their Lord! [Surah An-Najm. Aayaat 19-23]
The First Benefit:
Allaah [The Exalted] said: [إِنۡ هِىَ إِلَّآ أَسۡمَآءٌ۬ سَمَّيۡتُمُوهَآ أَنتُمۡ وَءَابَآؤُكُم مَّآ أَنزَلَ ٱللَّهُ بِہَا مِن سُلۡطَـٰنٍ – They [i.e. these idols and objects which you worship besides Allaah] are but names which you have named, you and your fathers, for which Allah has sent down no authority].
A great benefit is derived from the [above] statement of Allaah, because it distinguishes between truth and falsehood, and between guidance and misguidance. The sound Islamic Creed is what Allaah has ordained and sent down by way of revelation; and regarding the word [أَنزَلَ- sent down], it indicates to us [another] benefit – that the Creeds are two types: The creed ordained and sent down by Allaah as revelation [to the Prophets and Messengers], and the Creeds that are innovated [or concocted] by the people on the earth. Allaah said [in another Aayah] regarding the creed He ordained and sent down:
وَإِنَّهُ ۥ لَتَنزِيلُ رَبِّ ٱلۡعَـٰلَمِينَ
نَزَلَ بِهِ ٱلرُّوحُ ٱلۡأَمِينُ
عَلَىٰ قَلۡبِكَ لِتَكُونَ مِنَ ٱلۡمُنذِرِينَ
بِلِسَانٍ عَرَبِىٍّ۬ مُّبِينٍ۬
And truly, this (the Qur’an) is a revelation from the Lord of the ‘Alamin (mankind, jinns and all that exists), which the trustworthy Ruh [Jibrael (Gabriel)] has brought down; upon your heart (O Muhammad) that you may be (one) of the warners; in the plain Arabic language. [Surah Ash-Shu’araa. Aayaat 192-195]
As for the creeds that are innovated (or concocted) by the people in the earth, they are false because the one and only sound creed is that which Allaah sent down with authority [i.e. infallible and unquestionable proof]. Allaah [The Exalted] said: [إِنِ ٱلۡحُكۡمُ إِلَّا لِلَّهِۚ – The command (or the judgement) is for none but Allah] [Surah Yusuf. Aayah 40].
Every creed that has been innovated [or concocted] is false and rejected. [Allaah informed us that Yusuf (alayhis salaam) said to his fellow inmates in the prison]:
يَـٰصَٰحِبَىِ ٱلسِّجۡنِ ءَأَرۡبَابٌ۬ مُّتَفَرِّقُونَ خَيۡرٌ أَمِ ٱللَّهُ ٱلۡوَٲحِدُ ٱلۡقَهَّارُ
مَا تَعۡبُدُونَ مِن دُونِهِۦۤ إِلَّآ أَسۡمَآءً۬ سَمَّيۡتُمُوهَآ أَنتُمۡ وَءَابَآؤُڪُم مَّآ أَنزَلَ ٱللَّهُ بِہَا مِن سُلۡطَـٰنٍۚ إِنِ ٱلۡحُكۡمُ إِلَّا لِلَّهِۚ أَمَرَ أَلَّا تَعۡبُدُوٓاْ إِلَّآ إِيَّاهُۚ
O two companions of the prison! Are many different lords (gods) better or Allah, the One, the Irresistible? You do not worship besides Him but only names which you have named (forged), you and your fathers, for which Allah has sent down no authority. The command (or the judgement) is for none but Allah. He has commanded that you worship none but Him (i.e. His Monotheism). [Surah Yusuf. Aayaat 39-40]
Second Benefit Regarding The Statement of Allaah:
[إِن يَتَّبِعُونَ إِلَّا ٱلظَّنَّ وَمَا تَهۡوَى ٱلۡأَنفُسُۖ – They follow but a guess and that which they themselves desire]. There is a tremendous benefit derived from this, because the one deprived of sound Eemaan and the sound creed sent down as revelation by Allaah- The Lord of the Aalameen, then his affair is one of two: Corruption in Knowledge or Corruption in his Intent– corruption in knowledge occurs as a result of following conjecture and corruption in one’s intent occurs as a result of following desires, or the person may combine both of them.
Another benefit derived from this is that the rectification or well-being of a person cannot be attained except by way of two affairs: Upright [or sound] Knowledge and Upright [or sound] Intent. This is why Imaam Ibnul Qayyim (rahimahullaah) said in Miftaah Daarus Sa’aadah that a person is in need of two things: ‘[Sound] Knowledge by way of which he is [rightly] guided and lofty aspiration by way of which he is urged towards that [sound aspiration]’, because it maybe that a person has beneficial knowledge but not [sound] intent and aspiration. Therefore, one cannot be upright except by way of upright knowledge and intent. Sound knowledge is corrupted through following conjecture and sound intent is corrupted through following the desires of one’s soul.
Allaah [The Exalted] stated about the Messenger [sallal laahu alayhi wasallam]: [مَا ضَلَّ صَاحِبُكُمۡ وَمَا غَوَىٰ-Your companion (Muhammad) has neither gone astray nor has erred]. That is because the Daal [misguided person] is one whose knowledge is corrupted and the Ghaawiy [astray one] is the one whose intent is corrupted.
Also, the Prophet [sallal laahu alayhi wasallam] described his four khulafaa [Abu Bakr, Umar, Uthmaan and Ali (radiyallaahu-anhum)] with the words ‘Raashideen and Mahdiyyeen’, because the Raashid [i.e. The one who is steadfast upon the right path and is firmly established upon it] is the opposite of the Ghaawiy [The one who strays from the right path or conduct], and the Mahdee [The one guided to the path of truth and yeilds obediently to it] is the opposite of the Daalun [the misguided one, especially in knowledge and creed].
[An Excerpt from Sharh Kitaab At-Tawheed. Lesson 4. Slightly paraphrased]