Because Shariah of Islam is complete there is no need for any other Shariyah.
Since the Shariyah of Islam is the Haq till the day of Judgement and it is complete hence there is no need to refer to any other Shariyah, nor should one attempt to reconcile Islam by mixing practices of other beliefs with it (i.e. to believe democracy is acceptable in Islam).
Allah (swt) has revealed all the rules and regulations in Shariyah of Islam needed till the day of Judgement hence there is no need to refer to any other Shariyah.
An Ikhawani deviant said,
“Despite the fact that the Shariyah is a way of life, there many issues which the Shariyah never spoke about, therefore we need take from what intellectual schools have understood i.e. democracy, socialism or any other views from different schools of thought.”
This statement contradicts the belief that the Shariyah is complete and solution for all matters of life. The one who claims that the Shariyah of Islam is needy for man-made law has declared a statement which is Kufr akbar.
Then Shariyah of Islam is belongs to Allah (swt) and to Allah belongs the perfect names and attributes. It is an absurd notion to say Allah is perfect but His Shariyah has defection. To say one has defection in their word means defection in their attribute, and Allah (swt) is free from all defections. The Qur’aan is the Word of Allah and Sunnah is that which has been inspired by Allah and both are infallible.
The completion of the Deen necessitates one not to refer to any other Shariyah nor to introduce any new matters (Biddah) and claim it to be part of the Deen.
Ayesha (ra) reported that the Messenger Muhammad (saw) said:
“Whoever introduces into our matter (religion) that which is not a part of it, will have it (his innovation) rejected.”
The principle:- iktimaal ul Shariyah will prevent one from deviating towards any false ways, or to mix Islam will any false ways i.e. in Iraq, the governing body say Islam is one of sources of legislation. This is a Kufr notion because Islam should be the ONLY source of legislation.
History bears testament of the Shariyah of Islam. For over 1300 years Islam was implemented and was root cause for the prosperity of man in all fields of sciences i.e. biology, chemistry, astronomy, mathematics, economics, social well being etc. The only reason why no other Shariyah can compare to the greatness and perfection is because unlike other ways the Shariyah of Islam was chosen by the Most Perfect (Allah).
Islam abrogated all Shariyah before it and nullified any laws invented after it. However there is nothing wrong in benefiting from the scientific, mathematical, medical, technological discoveries made by the Kuffar in condition that it was permissible to do so according to the Shariyah.
In the history of Islamic rule, Islam spread from west of China all the way to Spain, the subjects of the state were from different backgrounds, dialects and languages. However all the people use to arbitrate to Islam in all matters of life. During the reign of the Khilafah the zakat use to be collected and distributed. In every region there were scholars, judges, and police etc. to govern the affairs of the people. During that period there was never a moment where people would seek the solution to their problems to any other Shariyah, they never went to the Kuffar to resolve their problems.
Abu Huraira narrated that the Prophet (saw) said,
“The Israelis used to be ruled and guided by Prophets: Whenever a Prophet died, another would take over his place. There will be no Prophet after me, but there will be Caliphs who will increase in number.” The Sahabah asked, “What do you order us to do?” Muhammad (saw) replied, “Give the bayah to the first one amongst them, and give them their own Haq (i.e. give him authority for his leadership as long has rules by Islam and to support, listen and obey in order to facilitate the implantation of the Shariyah). Allah is going to account them for what He put in the hand (i.e. the responsibility of ruling by Islam).”
Therefore issues of the duynah will only be governed in accordance to the Shariyah. When people separate dunyah from the Deen are in actual fact claiming that the Shariyah has no role to play in man’s life’s affair. In other words they are claiming there is Tawheed Rububiyah but no Tawheed Uluhiyah. And it is a known fact the majority of the Shirk is not committed in the Rububiyah rather it is in the Uluhiyyah.
The Deen came to manage all the affairs of man. Whoever denies or separates politics from the Deen has committed Kufr-Akbar (great evil [that equates to apostasy]), and this is the attribute of the secular people. The Ahkaam of the Deen cannot be restricted to only ritual acts only.
Allah (swt) said:
“And no example or similitude do they bring (to oppose or to find fault in you or in this Qur’aan), but We reveal to you the truth (against that similitude or example), and the better explanation thereof.”
We learn from this verse whatever the Kuffar proposed solution maybe, the Shariyah will always provide a better solution. The Kuffar can never compete with the Shariyah of Allah (swt). Therefore it is not allowed for any who believes that the Shariyah is perfect and competed, to change it or refer to any other way.
Many people fail to realise and submit to the famous principle ‘Islam is superior and nothing can supersedes it’. The messenger Muhammad (saw) came to destroy Shirk, kufr and Jahilliyah hence no other way/religion/ideology can supersede, overwrite, mix or co-exist with Islam.
Allah (swt) said,
“And most of them believe not in Allah except that they attribute partners unto Him [i.e. they are Mushrikun -polytheists].”
In this ayah Allah (swt) has explained to us that the majority of the people who believe in Allah (swt) are mushrikun because they mix Islam with something else.
How can the one who say he believes in Allah and His Word (Qur’aan), and then attempt to pollute it by mixing with that which from the Hawah (desires) of man?
The person who lives amongst the Kuffar and is satisfied with their way is a mushrik. The Prophet (saw) declared Baraa from the Muslim who were satisfied with the Kufr and Shirk.
The Prophet (saw) said:
“I have baraa (disassociation) from those who live between the mushrik and don’t distinguish themselves from them.”
There must always be a distinction between the Haq and the Baatil. Islam is the complete and perfect Deen unlike all the other present day beliefs and ideologies. Therefore Muslims must always distinguish themselves from the ways of the Kuffar.
In the Qur’aan Allah (swt) constantly makes the distinction between the Haq and Baatil,
“Say (O Muhammad (Peace be upon him) to these Mushrikoon and Kafiroon): “O Al-Kafiroon I worship not that which you worship, Nor will you worship that which I worship. And I shall not worship that which you are worshipping. Nor will you worship that which I worship. To you be your religion, and to me my religion (Islamic Monotheism).”
No matter what level of understanding a person may possess, all can acknowledge from Surah Kafiroon, that there can be no comparison between Islam and any other belief.
Allah (swt) endorses that judgement must be based upon Shariyah and not that which opposes it (i.e. Hawah),
“And so judge (you O Muhammad) between them by whatever Allah has revealed and follow not their vain desires, but beware of them lest they turn you (O Muhammad) far away from some of that which Allah has sent down to you. And if they turn away, then know that Allah’s Will is to punish them for some sins of theirs. And truly, most of men are Fasiqun (rebellious and disobedient to Allah).”
We must refer to shariyah at all time no matter what the situation may be. A person is not permitted to refer to any other Shariyah because in the verse Allah does not only say that judgement must be based upon Shariyah but Allah also orders not follow the Hawah. Allah (swt) ordains the believers to be aware of the Kuffar hence the believers must have absolute Baraa (disassociation) from that which is neither based upon Shariyah nor opposed to the Shariyah(if it is from the Kuffar).
Many from the current deviated sects call people towards the Hawah and prevent people from submitting to the Shariyah. In many instances these sects attempt to package their ideas by distorting the understanding of the text, only choosing those text which correlate with their way of thinking or giving precedence to the mind over the text.
If one wishes to make comparison between Ahl Biddah of the past and present one will conclude that all the innovated thoughts and ideas of today is linked to the deviation of the past, the only difference is that the sects of today have repackaged themselves with different names but in essence they are the similar to those of the past.
 Reported in Bukhari and in Muslim
 Reported in Bukhari, Volume 4, Book 56, Number 661
 Quran, Fuqan 25:33
 This principle is also a hadeeth of the Prophet (saw).
 Quran, Yusef 12:106
 Quran, Kafiroon 109:1-6
 Quran, Maidah 5:49