a) Islam is the name of all of the religions sent down through all prophets. (see al-Baqara, 130 – 133) Humanity came to the world with a prophet (Hz. Adam). Allah sent prophets with different shari’ahs (laws) based on the conditions of the time and the needs of humanity; however, creed (belief) was the same for all prophets.
b) The religions conveyed by the previous prophets had been sent to certain nations. The religion sent to Hz. Muhammad (pbuh) is a universal religion. That is, it was presented to the whole universe and humanity by Allah; it is a way of life that will be valid until Doomsday.
c) The religion of Islam, which Hz. Muhammad (pbuh) conveyed, abrogated the decrees (shari’ahs) of the religions conveyed by the previous prophets. That is, what is valid today is the shari’ah of Hz. Muhammad (pbuh).
Some Verses on Islam
“If anyone desires a religion other than Islam (submission to Allah) never will it be accepted of him; and in the Hereafter he will be in the ranks of those who have lost. (all spiritual good).” (Aal-i Imran, 3/85)
“…This day have I perfected your religion for you, completed my favour upon you, and have chosen for you Islam as your religion…” (al-Maida, 5/3)