The world made great mistake - maybe some can see it today - by the abolishment of the institution of the Caliphate in 1924 and with the artificial introduction of Western type republics or monarchies in the Islamic world. The terminologies of caliphate and sharia are included in the Quran! Interfering into this is a historical mistake!

1. The following quote describes the scene in the Heaven. God speaks to angels before the creation of Adam:

Behold, thy Lord said to the angels: "I will create a vicegerent on earth." They said: "Wilt Thou place therein one who will make mischief therein and shed blood?- whilst we do celebrate Thy praises and glorify Thy holy (name)?" He said: "I know what ye know not." (Quran 2:30)

Adam was created by the Lord as a caliph (procurator) to make His Guide available to mankind. خلف (khalf) means behind and خليفة) khalifa or caliph) means successor who represents the Lord in His behind. Here, too, I would like to dispel the concept that Islam is counted from Mohammed (peace be upon him). In our view, Islam existed forever in the material world and is constantly here in the world of mankind since Adam and Eve. Caliph is the chief among people who makes the law (fiqh) taking in consideration the doctrines of the Lord (aqida) and the order of divine legitimacy (sharia), and this law is always adapted to a given age and place. Within this conceptual system were Abraham, Isaac, Ishmael, Moses, Jesus all Caliphs, and even the first Islamic kingdoms of the earth were established by David and Solomon, who both - even if it is strange for you - were kings according to the order of Islam. Were they not subordinated their kingdom to the One God? Do you dispute about it? If you can't dispute it, then this is called in Arabic Islam and even according to the Islamic definition of its essence is Islam as well! Prophet Muhammad (peace be upon him) was a Caliph in this sense, for he made law according to the doctrines and divine order of legitimacy based on the Quran. Here you are:

Then We put thee on the (right) Way of Religion: so follow thou that (Way), and follow not the desires of those who know not. (Quran 45:18)

The quoted Arabic text also includes the word sharia! The Quran cannot be rewritten, nor can its words be exchanged with others, such as democracy or republic.
The Caliphate was the institution that could have modernized the perception of Islam. The scholars of Islamic law (fuqaha) of the Caliphate shaped the law to be appropriate for the time.
The Caliphate could have secured coexistence, and if its legal side was managed by scientists, together with scientists of secular law they could have created "sharia compliant" law system which is analogous with the secular laws in terms! The abolition of caliphate is similar to the abolition of the "Voivode" institution among Gypsies.
The consequences are tangible both in case of the Gypsies as well as in the thinking of Muslims. As a matter of fact, there are those who integrate, but the majority are not able to become European lawfollowers, either because of historical reflexes or due to the comprehension and diversity of legal terminologies in the community. Not because they don't want to, but because they are not able! At least for a couple of generations they cannot change. And if it remains so, masses of parallel societies will be formed. And that won't be good for anyone.

Two sides must work together:

1. The integrating societies must realize that they cannot do with Muslims what they did with Christians. It is not possible to create shallowness in this belief with spectacle, show elements, Hollywood cinema-effects, cathartic scenes, music and dance. Why not? It's because Muslims are practicing Islam on mass basis. They are not Sunday temple-visitors, but everyday faith-practitioners. Such attempts will lead to radicalization. Once the Caliphate as a legal institution is no longer exists, it is necessary to begin a process of legislative harmonization in which we bring our legal interpretations under the similar direction.
2. Muslims also need to reassess their current knowledge of Islam. Besides of memorizing the sacred texts, it is also worth to go deep in understanding of the Quran. It is time to realize that we are our own enemies due to our ignorance and not others are our enemies. Our emblematic scholars should not be driven by the pursuit of popularity, or causing disintegration in the society, but the intention of cooperation. We must be rid of the preachers who cause segregation for Muslims and are responsible in the creation of parallel societies. Collaboration requires knowledge. Not only Islamic knowledge, but also secular knowledge. Dialogue can only take place if both parties are familiar with both languages, terminologies and concepts.

In the Iberian Caliphates, Jews, Christians and Muslims have been harmonizing law for 800 years. That was the case in Baghdad as well and during Fatimids in Egypt and I could list more. By the 15th century, Suleiman the Great had practically secularized the Caliphate. He reigned as the possessor of earthly power, that's what the word sultan means and he was not a Caliph. He placed the control of religious life in the hands of Islamic scholars and muftis, which he did not deal with. Whatever era I study, I find thousands of examples of legal harmonization what was taken place with the method of deductive analogies (Qiyas). All this has not happened since 1924.

Israel has inherited part of the Ottoman tradition. They transfer Muslim family law, conciliation and arbitration issues, and special cases that the majority society does not want to deal with, to the treatment of the community itself. There is a Sharia court in Israel whose members, its president, get their legitimacy from the president of Israel. Of course, the Sharia court cannot override the laws of majority society, and it works in harmony with it.
There are many ways we can live together. With fences, trenches, segregation, hatred, publishing hostile literature, slandering each other and behind all of these there are enough political intentions.
I would like to suggest one that does not segregate but brings us closer and is offered by the Islam itself. I suggest legislative harmonization. It is essential for the non-Muslim side to get used to the positive interpretation of the word sharia, and for the Muslim to understand that his knowledge about sharia is past, inapplicable and is impossible to follow. I emphasize, I said: what Muslims know about sharia today! I didn't say sharia.
I ask Allah to accept my thoughts and forgive me if I was wrong.