Is Islam and faith specific to the message of our Prophet Muhammad, may Allah’s prayers and peace be upon him, or do they include everyone who worshipped Allah in any form before and after the Prophetic mission?

Before the advent of the Prophet Muhammad, peace be upon him, everyone who believed in the previous messengers and died upon that belief would enter Paradise. However, after his advent, no one will enter Paradise except those who follow him, peace be upon him, as he said: "All of my Ummah will enter Paradise except those who refuse." It was asked, "O Messenger of Allah, and who would refuse?" He said, "Whoever obeys me enters Paradise, and whoever disobeys me has refused." And also because he said: "By Him in whose Hand is my soul, no one from this nation, neither a Jew nor a Christian, hears of me and then dies without believing in that with which I was sent, but he will be among the people of the Fire."

As for those who did not receive his call, "the people of the fatrah (interval)," their matter is with Allah; He will test them on the Day of Resurrection.

It is obligatory to declare as disbelievers those to whom the message of the Prophet, peace be upon him, reached and they disbelieved in it. The Prophet, peace be upon him, said: "Whoever affirms the Oneness of Allah and disbelieves in what is worshipped besides Allah, his wealth and blood are inviolable, and his reckoning is with Allah." And Allah Almighty says: "So whoever disbelieves in Taghut and believes in Allah has grasped the most trustworthy handhold with no break in it. And Allah is Hearing and Knowing." Therefore, whoever receives the message of Allah and does not believe is among the people of the Fire.