Allah (Exalted be He) has sent the messengers as givers of glad tidings, and warners, and sent down the Books (Part No. 3; Page No. 523) so that mankind would have no plea against Allah after sending the messengers. Allah guides whomever He wills among His servants to Iman by His Grace and Bounty. On the other hand, He does not guide others to Iman due to His Wisdom and Justice. Allah says,
Allâh calls to the Home of Peace (i.e. Paradise, by accepting Allâh’s religion of Islâmic Monotheism and by doing righteous good deeds and abstaining from polytheism and evil deeds) and guides whom He wills to the Straight Path.
Allah knew before He created people that there will be believers among them who will enter Jannah and disbelievers who will enter Hellfire.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.