The holy Qur’an makes mention,” Lo! religion with Allah (is) the Surrender (to His Will and Guidance). Those who (formerly) received the Scripture differed only after knowledge came unto them, through transgression among themselves. Whoso disbelieveth the revelations of Allah (will find that) lo! Allah is swift at reckoning”. (The Family of Imran) 3:19
These verses reveal that the religion with Allah is only Islam but as we see that people follow many religions rather than Islam in the world i.e. Christianity, Judaism, Buddhism, Shinto, Sikhism, Confucianism, Jainism, Hinduism and Taoism etc.
The question arises here that why do people follow the various religions for worship and what is the reason behind it? So, the reason is that every man has a sense of worship into him, it means he seriously wishes that he should bow down and or to prostrate before a Supernatural being.
That is why when any ruins of ancient civilization are discovered in any part of the world, a temple also exists in it in which people used to worship according to their belief.
Now the question is: where from this sense of worship has been created in man, so the holy Qur’an reveals,” And (remember) when thy Lord brought forth from the Children of Adam, from their reins, their seed, and made them testify of themselves, (saying): Am I not your Lord? They said: Yea, verily.
We testify. (That was) lest ye should say at the Day of Resurrection: Lo! of this we were unaware; Or lest ye should say: (It is) only (that) our fathers ascribed partners to Allah of old and we were (their) seed after them. Wilt Thou destroy us on account of that which those who follow falsehood did? (Al-A'raf (The Heights) 7:172 ).
Narrated Abu Huraira:
Allah's Messenger (ﷺ) said, "Every child is born with a true faith of Islam (i.e. to worship none but Allah Alone) but his parents convert him to Judaism, Christianity or Magainism, as an animal delivers a perfect baby animal. Do you find it mutilated?"
Then Abu Huraira recited the holy verses: {فِطْرَةَ اللَّهِ الَّتِي فَطَرَ النَّاسَ عَلَيْهَا لاَ تَبْدِيلَ لِخَلْقِ اللَّهِ ذَلِكَ الدِّينُ الْقَيِّمُ} "The pure Allah's Islamic nature (true faith of Islam) (i.e. worshipping none but Allah) with which He has created human beings. No change let there be in the religion of Allah (i.e. joining none in worship with Allah). That is the straight religion (Islam) but most of men know, not." (30.30)
Every child born on the right nature means that every child born with a true faith of Islam because he has seen Allah Almighty already at the “yaume alast“ and has testified about Him as being his Lord and The Creator of the world and that is why the foundation of Islam is rooted in his heart.
But when he becomes a young, he adopts his forefather’s religion automatically. But reality is: the passion, devotion and longing of Islam exists in his heart yet. That is why in most cases, we see that many people try their best to study and understand Islam and at last they accept or convert to Islam.