Why are people who convert to Islam referred to as ‘reverts’ by many Muslims?
In order to answer that, there's a side of Islam's sense of itself that needs to be understood. Which is: to be a good Muslim, one must believe in "Fitrah".
‘Fitrah’ is the Islamic notion that every child is born in a state of spiritual purity that includes a belief in the Islamic conception of God. Basically, the word 'Fitrah' is similar to the concept of 'human nature' but in Islamic doctrine Islam itself is assumed to be 'human nature'. Meaning the religion of Islam considers and preaches itself to be the "natural" state of humans.
So where does this leave non-Muslims?
Let's look at a hadith that is considered to be Muhammad's point of view.
From Sahih al-Bukhari, Volume 2, Book 23, Number 441
"Abu Hurairah narrated: Allah's Apostle said, 'No child is born except on the fitrah and then his parents make him Jewish, Christian or Magian (Zoroastrian), as an animal produces a perfect young animal: do you see any part of its body amputated?'"So the idea is, when someone converts to Islam, he or she ‘reverts’ to the natural state they were born in, which was the state of being Muslim or believing in the Islamic idea of God.
This suggests that to be Muslim is to be truly human. Or conversely, to be truly human, one must be a Muslim.In other words, Islam presents itself not just as a religion, but as being the naturally created state of a human being.
To be non-Muslim then is not only to deviate from the one true belief system, but to deviate from the very basic definition of being human.
Islam, according to this view, can never be just a private religious faith. Its fundamental drive to take 'deviated' non-Muslims and make them fully human by having them convert to Islam is what is the drive behind the practice of Dawah, or Islamic proselytizing.
This is problematic for many reasons.
It is prejudiced, supremacist, and dehumanising. It divides humanity into believers in Allah who are fully realised humans on the one hand, and non believers, who are seen as deviant, unrealised humans on the other hand.
It also suggests that those who leave Islam are taking themselves outside of the ‘true human’ fold.
The concept of 'Fitrah' puts a religious rubberstamp on dehumanising of apostates and Exmuslims.
How then can one believe in Fitrah and also believe that all humans are equal at the same time?
To assert that to be fully human is to be Muslim is to assert that non-Muslims are not fully human.
This can only mean that all non-Muslims are are not fully human, rather than merely people with different religious beliefs.
And so, when Muslims refer to converts as ‘reverts’, they are saying exactly that. They are in essence dehumanising non-Muslims and ex-Muslims.
This belief must be challenged. Not only is it delusional and arrogant, it is the fountainhead of prejudicial assumptions about non-Muslims, and all that is not Islam.
When so much arrogance and prejudice hides behind a single word, we should not be afraid to refuse it the power it seeks. To let it pass unchallenged is to surrender the humanity and dignity of those whom it would deny.
There is nothing in human nature that requires belief in Allah or Islam, or any religion. To assert otherwise is to be an arrogant supremacist.