Answered by: Maulana Irfan Ali
Why was Ramadan called Ramadan even before Islam? Keeping the literal meaning in mind (رمض to burn), not everyone fasted before Islam and the burning of sins is exclusive to Muslims, so why is it called Ramadan when not everyone fasted before Islam, hence their sins didn’t burn?
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
Historians state that the first person to fast Ramadan was the Prophet Nuh when he left the Ark. Imam Mujahid said that Allah made fasting the month of Ramadan obligatory for every nation and it is known that there were nations before Nuh and Allah knows best. The word for the month, Shahr, is derived from ishhiir which means to make something known in such a way that it is not difficult for anyone to know it. The verb is also used for a sword being unsheathed.
The name Ramadan is derived from ramad which is burning, because the belly of the faster is burning from thirst. Ramad is intense heat. It is said that the month was named because it was the time of intense heat. It is said that it is called that because it bums up wrong actions by righteous actions. It is said that it is because, in it, the hearts take the heat of admonition and reflection about the Next World as the sand and stones are burned from the heat of the sun.
From Imam Qurtubi’s explanation, it is quite clear that the removal of sins was not confined just to Muslims but to previous nations also.
Only Allah knows best
Written by Maulana Irfan Ali
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Tafsir Qurtubi vol 2 page 282