Why is the crescent used in the Muslim Religion. When was it first used.?

Salam.The crescent moon is used in the Islam religion especially in the top of the roof of the mosques as symbol of the creation of Allah.The first used of this symbol was in Turkey

For the Abrahamic religion the Lunar Calendar is being used .

Since the Jews used the New Moon to fixed their first day of the month but for Muslims, prophet Muhammad (PBUH) fixed the first day of the Lunar month by sighting the first Cresent Moon ,as a religious principle , according to the commandment of GOD in Al-Quran .

So it was started using since the time of the Prophet, 1400 years ago up till now and will continue till the end of the world.

It is in fact one of the oldest icons in human history, having been known in graphic depictions since at least as early as the Babylonian period in Mesopotamia. The stele of Ur Namu, for example, dating from 2100 BC, includes the crescent moon to symbolise the god Sin, along with a star representing Shamash, the sun god. Later the moon became a female deity, typified by the goddess Artemis and her many counterparts, including Diana, who was celebrated as the moon-goddess in Roman times and depicted with a crescent on her brow. The device seems to have entered Islam via the Seljuk Turks who dominated Anatolia in the 12th century, and was widely used by their successors, the Ottoman Turks, who eventually became the principal Islamic nation, and whose Sultan held the title of Caliph until 1922

The crescent is completely irrelevant to Islamic faith.It was first used by Ottomans and was adopted from a city they conquered; It wasn't until the Ottoman Empire that the crescent moon and star became affiliated with the Muslim world. When the Turks conquered Constantinople (Istanbul) in 1453, they adopted the city’s existing flag and symbol.

It's from the Ottoman Empire. The symbol is not Islamic

Ottoman neggas adopted it ! It's got nothing to do with Islam

it was originated by Ottoman empire.

It goes back when the Turks and Arabs were praying to the moon god.