أَفَغَيْرَ دِينِ اللَّـهِ يَبْغُونَ وَلَهُ أَسْلَمَ مَن فِي السَّمَاوَاتِ وَالْأَرْضِ طَوْعًا وَكَرْهًا وَإِلَيْهِ يُرْجَعُونَ ﴿٨٣﴾ قُلْ آمَنَّا بِاللَّـهِ وَمَا أُنزِلَ عَلَيْنَا وَمَا أُنزِلَ عَلَىٰ إِبْرَاهِيمَ وَإِسْمَاعِيلَ وَإِسْحَاقَ وَيَعْقُوبَ وَالْأَسْبَاطِ وَمَا أُوتِيَ مُوسَىٰ وَعِيسَىٰ وَالنَّبِيُّونَ مِن رَّبِّهِمْ لَا نُفَرِّقُ بَيْنَ أَحَدٍ مِّنْهُمْ وَنَحْنُ لَهُ مُسْلِمُونَ ﴿٨٤﴾ وَمَن يَبْتَغِ غَيْرَ الْإِسْلَامِ دِينًا فَلَن يُقْبَلَ مِنْهُ وَهُوَ فِي الْآخِرَةِ مِنَ الْخَاسِرِينَ
Are they, then, seeking a religion other than that of Allah Ta‘ala, while to Him alone submit all those in the heavens and the earth, willingly or unwillingly, and to Him they shall be returned? Say, “We believe in Allah and in what has been revealed to us and in what was revealed to Nabi Ebrahim (‘alaihis salaam), Nabi Ismaa‘eel (‘alaihis salaam), Nabi Ishaaq (‘alaihis salaam), Nabi Ya’qoob (‘alaihis salaam) and the descendants, and in what has been given to Nabi Moosa (‘alaihis salaam), Nabi ‘Isa (‘alaihis salaam) and the prophets, from their Rabb: We do not differentiate between any of them; and to Him we submit ourselves.” Whoever seeks a faith other than Islam, it will never be accepted from him, and he, in the Hereafter, will be among the losers. (Surah Aal-‘Imraan v83-85)
Before Rasulullah (sallallahu ‘alaihi wasallam), Allah Ta‘ala had sent many Ambiyaa (‘alaihimus salaam) to the world for the guidance of mankind. Different nations and tribes had their own Ambiyaa and would follow the laws and injunctions that were revealed to them by Allah Ta‘ala. Since all the Ambiyaa (‘alaihimus salaam) were sent by Allah Ta‘ala and gave people the same message – to worship Allah Ta‘ala alone, we bring imaan in all of them.
After the advent of Rasulullah (sallallahu ‘alaihi wasallam), Allah Ta‘ala commanded that all the people of the world, regardless of nation, tribe or race, submit to his Deen – the Deen of Islam – and follow his blessed sunnah. Hence, the coming of Rasulullah (sallallahu ‘alaihi wasallam) brought an end to all other religions. Now, Allah Ta‘ala will not accept any Deen besides the Deen of Islam. Thus, there is no other Deen or way through which one can gain salvation and entry into Jannah besides the Deen of Islam and Sunnah of Rasulullah (sallallahu ‘alaihi wasallam).