Iranian scholar Dr. Manouchehr Sadeghi has several points to achieve strong unity.

"As you see, followers of all Islamic religions are Muslims and deserve Islamic and religious respect. Followers of any school of thought should respect both those of their own faith and those believing in other schools of thought because any discrimination in the respect means denial of Muslim value of the followers of Islamic schools of thought," he noted.
Sadeghi stated, "To this end, Muslims have the duty to respect each other and no one shall avoid helping Muslims under pretext of difference in school of thought; so, Muslims’ caring each other is compulsory and their distancing from each other is forbidden. Not only Muslims should not far apart of each other but also, they should not distance themselves from those believing in the same faith under pretext of having religious difference. Rather, they should treat followers of other faith in the same way of treating those of common faith."

The Islamic thinker went on to say, "Besides Muslims’ duty to respect each other based on Islamic jurisprudence, all faiths have equal rights. All these show that under all conditions, we are in equal conditions; Now that followers of Islamic schools of thought are in equal condition when the obligation for mutual respect based on Islamic rights is concerned.


"The artificial geographical borders of followers of Islamic schools of thought need to be separated. Each of the Hanafi, Shafei, Maleki, Hanbali, Seyedi, Imami, Twelver Shia (Asna Ashari) schools live in an environment and after unwanted appearance of artificial borders, Muslims started to feel alien to each other. All these show that Muslims share abundant commonalty. So, we should take action based on commonalty and rely on them."
To achieve strong unity, I suggest you a series of points, which I hope will be taken into consideration:  
 
First of all, dialogues should be held on issues of difference. Abdulhakim Mohammad Abu Shafe says, “We should help each other in issues of consensus and hold talks on issues of discord.”
Second: Avoiding going astray
There are a group of astray people in any religion and school of thought. We should distance ourselves from them. Before anything, we need to learn about the concept of going astray and its instances in the best possible manner in Quran, tradition and sense so as not to accuse anybody of being so.
Third: Avoiding tricks of Islam’s enemies
God Almighty says, “And do not dispute, so you fail and your strength goes away.” Sowing discord and ruling have since long ago been the policy of enemy. This means that enemies divide Muslims to attain their dirty intentions.
Fourth, the need for single voice at time of hardship and feeling danger
God Almighty says, “Surely Allah loves those who fight in His cause in ˹solid˺ ranks as if they were one concrete structure.” God also says in holy Quran, “Muhammad is the Messenger of Allah; and those with him are forceful against the disbelievers, merciful among themselves.”
Sixth: Avoiding using sensitive and hateful words for each other
When confronting the opposition or when writing a book and analyzing an article, we should try to avoid hateful and sensitive words in connection with the other party. I mean the unpleasant words, which make the other party unhappy and do not help unity and only cause dispersion while showing impoliteness to the other party in talks, should be avoided.
The 7^th point is avoiding desecrating sanctities of the other party
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Avoiding cursing the sanctities is among ways for proximity of religions and schools of thought because he will also be provoked and insult your sanctities. God Almighty says,” ˹O believers! ˺ Do not insult what they invoke besides Allah or they will insult Allah spitefully out of ignorance.”
The next point is observing Islamic ethics in relation to each other. We should observe the least Islamic morals in relations with each other.
This is one of the very necessary issues in interviews and talking; and writing book and article and speech in general assemblies and private sessions.
The other point is meeting and talks; the outstanding example of this is the conferences which we take part in them and have face-to-face meeting with friends, scientists, thinkers and authors, thus affording great help to unity.
In margins of the book of Aldowr va Alkameneh of Ibn Hajar Aqlani says:
Surely, Ibn Motahhar Allameh Helli performed Hajj on the last period of his life. After his Hajj, he and Ibn Taymeyeh met and held talks. Ibn Taymeyeh was surprised of his words and asked, “Who are you, o man?” He said, “I am the one who you had called him Ibn al-Munjas. It was the time when the two were in good relationship.”
The next point is for other expressions
Any faith and clan have their own expressions for a number of ideas and Shariah. Before judgement, one should have necessary and enough information about the expressions of the faith; otherwise, they will reach Takfir and unjustifiably interpret each other. We should be very sensitive of the issue and know expressions well and then judge and apply them.
Unity of expressions is the next issue.
Other way for political integration of Islamic schools of thought is equalizing expressions in different Islamic schools of thought because various reforms and different interpretations may have drastic impact in misunderstanding and charges.
The other point is dealing with important issues.
A way of political integration is dealing with important issues and abandoning minor issues.
Dealing with minor issues will be of no use and we will deal with just issues that are not necessary and will solve no problem in the world of Islam. We should solve key issues and essential problems of Islam in today’s world and through dialogue we can raise single voice.
The next point is cooperation in incidental issues.
We should be able to highlight the issues of commonalty, which are not few but many; we should cooperate with each other to have good cooperation in that connection.
The next point is understanding people’s capacities.
When ordering others, a person should consider their capacity and not to rule everybody similarly; why? Because there are different groups of people in our society; attitudes are different and they have different opinions.
So, when speaking, we should consider capacity of the attendants of a meeting so as to insinuate what we wish so as to gain the expected results. 
The other point is being lenient.
Certain people use nonsense and absurd words, which ironically have extensive meaning, to name others heresy. They extend the word to include anything happening. Those words were not at time of prophet, calling it an incident. They do this to dictate their opinion to the addressee. More important is making today society understand what they wish and say what is done is an instance of heresy.
And last point is non-multiplicity in Ijtihad issues.
Today Mostahedeseh and Ijtihad issues are not rare in society. Anything that would succeed in controlling issues, even if extremism, to some extent, is avoiding Takfir in Ijtihad issues.
We should try to define Ijtihad issues in a way that it will not lead others to interpret it to be Takfir.
The last point is getting away of internal desires.
Criticizing the polytheists, God says in Quran, “They follow nothing but ˹inherited˺ assumptions and whatever ˹their˺ souls desire.”
God forbids not, we should not follow internal desires because they detach us from Quran and traditions of Holy Prophet of Islam (PBUH) and we should not interpret issues with respect to our soul. Without God’s book and tradition of prophet, the issues will create problems.