Why are converts to Islam called reverts?

The term "revert" is often used to describe converts to Islam because of the belief in Islamic teachings that all humans are born with an innate inclination toward monotheism, known as "Fitrah." This concept suggests that every person is born with a natural disposition toward recognizing and worshiping one God.

In this perspective, when someone converts to Islam, they are not adopting a new faith per se, but rather returning to their original state of belief in Allah, which they may have veered away from due to various influences in life. As stated in a narration from Abu Huraira in Sahih al-Bukhari, the Prophet Muhammad ﷺ remarked: Every child is born with a true faith of Islam (i.e. to worship none but Allah Alone) but his parents convert him to Judaism, Christianity or Magainism... Sahih al-Bukhari 23:441. This saying underlines the belief that individuals are born with the essence of faith, and any deviation from that is a result of external influences rather than an inherent nature.

From an Islamic theological standpoint, this understanding emphasizes the idea that reverting to Islam is a return to one's true nature and original faith, hence the terminology of "reversion" rather than "conversion."