Many verses of the Qur'an address the topic of good and bad people oppressors and oppressed in most cases (if not all) the oppressed ones are believers and the oppressors disbelievers. 

As politics and other customs and whatever is part of the local interpretation of Islam is off-topic. I'm afraid that one could hardly answer this without going a bit deeper on either of that.

Note that in Islam or by qur'an Mulsim's are asked to be like one heart and soul they should be strong against their adversary who ever it might be and show power. They should apply justice for all the people (Muslims in first place) based on the qur'an and sunnah (the sunnah tell us to apply the rulings Torah on Jews so one may use this in analogy). Does this apply to the actual Muslim Ummah? **NO**.  

So basically answering the question means that Muslims should in first place repair the above deficits. As Allah says in the Qur'an:
> ...  Indeed, Allah will not change the condition of a people until they change what is in themselves. And when Allah intends for a people ill, there is no repelling it. And there is not for them besides Him any patron. ([13:11][1])

We may also find verses that explain that once Muslims get astray from that which was revealed to them, they are responsible for what happened to them. The Muslim history shows that when the Muslims as a nation were strong when they abide to the rulings of Islam wherever they were in our outside a Muslim country.

Muslims might be a big majority of human beings but they are still scattered and divided in different nations, countries in which Islam hardly plays a bigger role than being a private matter or when it comes to punish -mostly weak- wrongdoers and they are even oppressed in their own lands. In some so called theocracies actually the scholars actually support the governments in other countries the governing people have chosen scholars or oppressed them to support their view or defend them.  
So sadly in most cases those who try to follow the rulings of Islam do it based on half-knowledge and in an unorganized manner. And they might apply one ruling and forget others (->Injustice->Oppression: vicious cycle). As long as this will be the case and as long as oppression of Muslims is applied in their homelands the persecution of Muslims no matter where will hardly stop.

I'd say you could also read my answer on https://islam.stackexchange.com/questions/45286/what-does-the-hadith-about-paradise-surrounded-with-hardships-and-jahannam-surro/49653#49653 as a part of the answer.


  [1]: https://legacy.quran.com/13/11