It is a proven fact from the Holy Quran and Ahadith that the parents of the Holy Prophet, Mahboob-e-Kibriya, Muhsin-e Insaaniyat, Shafee-ul-Muznibeen, Rahmatul-Lil-Aalameen, Huzoor Pur Noor, Muhammadur Rasoolullah (sallal laahu alaihi wasallam) -Sayyiduna Abdullah and Sayyidah Aamina (radi Allahu anhuma) - were always on Imaan and left this world with Imaan.
Just as the cities of Makkah and Madina are the most exalted cities in the world due to being the birth place and place of demise of the Prophet (sallal laahu alaihi wasallam), likewise, the genealogy of the Holy Prophet (sallal laahu alaihi wasallam) is the most exalted and pure chain in the Universe. All his forefathers, from his father, Hazrat Abdullah (radi Allahu anhu), to Hazrat Adam (alaihis salaam), were Mu'min, Muwaahids (believers in the Oneness of Allah), Aabids and Zaahids. None from amongst them were idol-worshippers or Faasiqs (sinners). Actually, the Noor of Rasoolullah (sallal laahu alaihi wasallam) travelled from Hazrat Adam (alaihis salaam) to Hazrat Abdullah (radi Allahu anhu), in the family chain of those who always sincerely worshipped One Allah.
For those who say, Ma'az-Allah, that the parents of the Prophet (sallal laahu alaihi wasallam) were non-believers, they should think and ponder that if the parents of no other Prophet were non-believers, how then would the parents of the Greatest of all Prophets be non-believers?
Those who reject the teachings of the Prophets are regarded as Kaafirs and sinners. In the era of the Prophet's (sallal laahu alaihi wasallam) parents, his parents had not need bring Imaan on any Nabi as the true teachings of the Ambiya before their time had been changed. Further, when Nabi (sallal laahu alaihi wasallam) his Prophethood was not announced. In the era in which his parents lived all that was required for Imaan was to affirm the true belief in the Oneness of Almighty Allah. Neither did they commit Kufr nor was their Imaan changed, so they cannot be regarded as sinners or Kaafirs. They remain true Mu'mins in life and when they passed away.
The great Ulama have proven the Imaan and Islam of the parents of the Prophet (sallal laahu alaihi wasallam) in three different ways:-
Both of them were on Deen-e-Haneef - the teachings of Hazrat Ibraheem (alaihis salaam).
In their time, they had not received direct invitation of previous prophets to their Deen. They passed away with Imaan, believing in One Allah before the Prophet (sallal laahu alaihi wasallam) announced his Prophethood.
Due to the Du'a of Rasoolullah (sallal laahu alaihi wasallam) Almighty Allah gave life to his parents who were buried in their graves and they brought Imaan on him.
Almighty Allah granted life to the parents of the Holy Prophet Muhammad (sallal laahu alaihi wasallam) even after they had passed away to show them his status. Just as Almighty Allah brought back to life a person of the Bani Israel to show who killed a certain person; just as Hazrat Esa (alaihis salaam) brought the dead back to life; just as the Prophet's (sallal laahu alaihi wasallam) Du'a brought back many dead persons to life; just as the Prophet (sallal laahu alaihi wasallam) brought back the sun from West when the Asr Salaah of Hazrat Ali (radi Allahu anhu) became Qaza, likewise, his Du'a brought back his parents to life so that they may also bring Imaan on him.
Almighty Allah blessed the Prophet (sallal laahu alaihi wasallam) with acceptance, exaltedness and elevated his status. All the above mentioned facts proves that the Prophet's (sallal laahu alaihi wasallam) parents passed away as Mu'mins and Muwaahids. After Hajjat-ul Widaa, he brought them back to life with the permission of Allah. By seeing him and bringing Imaan on him, they became Sahaabi-e-Rasool (sallal laahu alaihi wasallam). May Allah bless us with strong Imaan in this world and may we leave this world with Imaan. Ameen. (For more details refer to "Fatawa Razviah"; "Tafseer-e-Na'eemi")
