Surah Yunus, Ayat 99

Ayat 99. And had your Lord willed, those on earth would have believed, all of them together. So, will you (O Muhammad ) then compel mankind, until they become believers. 

Hazrat Abu Huraira (May Allah be pleased with them) reported: Messenger of Allah  [SAWW](PBUH) said, There is none born but is created to his true nature (Islam). It is his parents who make him a Jew or a Christian (or a Polytheist) or a Magian quite as beasts produce their young with their limbs perfect. Do you see anything deficient in them? Then he quoted the Quran., The nature made by Allah in which He has created men there is no altering of Allah's creation; that is the right religion" (xxx. 33). [Muslim Volume 3, Book 33, Number 6423].  

Lesson : as mentioned above in Surah Yunus Ayat 99. "And had your Lord willed, those on earth would have believed, all of them together."

This Hadith brings out the following point: Only Allah has a power to guide any to the true path the right path is Knowledge and understanding of Deen (religion) here stands for the understanding of the Qur'an and Hadith, religious injunctions, and knowledge of the lawful and the unlawful.