The mother of every person gives him birth according to his true nature. It is subsequently his parents who make him a Jew or a Christian or a Magian. Had his parents been Muslim he would have also remained a Muslim. Every person to whom his mother gives birth (has two aspects of his life) ; when his mother gives birth Satan strikes him but it was not the case with Mary and her son (Jesus Christ).  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ كُلُّ إِنْسَانٍ تَلِدُهُ أُمُّهُ عَلَى الْفِطْرَةِ وَأَبَوَاهُ بَعْدُ يُهَوِّدَانِهِ وَيُنَصِّرَانِهِ وَيُمَجِّسَانِهِ فَإِنْ كَانَا مُسْلِمَيْنِ فَمُسْلِمٌ كُلُّ إِنْسَانٍ تَلِدُهُ أُمُّهُ يَلْكُزُهُ الشَّيْطَانُ فِي حِضْنَيْهِ إِلاَّ مَرْيَمَ وَابْنَهَا  

The mother of every person gives him birth according to his true nature. It is subsequently his parents who make him a Jew or a Christian or a Magian. Had his parents been Muslim he would have also remained a Muslim. Every person to whom his mother gives birth (has two aspects of his life) ; when his mother gives birth Satan strikes him but it was not the case with Mary and her son (Jesus Christ). (Using translation from Muslim 2659a)   

أَنَّ رَسُولَ اللهِ ﷺ قَالَ كُلُّ إِنْسَانٍ تَلِدُهُ أُمُّهُ عَلَى الْفِطْرَةِ أَبَوَاهُ يُهَوِّدَانِهِ أَوْ يُنَصِّرَانِهِ أَوْ يُمَجِّسَانِهِ فَإِنْ كَانَا مُسْلِمَيْنِ فَمُسْلِمٌ كُلُّ إِنْسَانٍ تَلِدُهُ أُمُّهُ يَلْكُزُهُ الشَّيْطَانُ فِي حِضْنَيْهِ إِلَّا مَرْيَمَ وَابْنَهَا