A lot of people have asked themselves this question, including myself. And that is one of the hardest questions to answer. Because Allah is able to guide who he wants. He mentions this himself in the Quran:
Those who associated with Allah will say, “If Allah had willed, we would not have associated [anything] and neither would our fathers, nor would we have prohibited anything.” Likewise did those before deny until they tasted Our punishment. Say, “Do you have any knowledge that you can produce for us? You follow not except assumption, and you are not but falsifying.”
Say, “With Allah is the far-reaching argument. If He had willed, He would have guided you all.”
Surah Al-Anam (6 – 148-149)
However, when you think of it, it is like saying why go to school to flunk your exam? The point is that you don’t go to school to flunk; you go to school to learn and to succeed. Everyone has the opportunity to succeed. If you listen in class, study hard, do your homework, go to tutoring; you might not get 100%, but you are pretty confident to pass your exam. Often, even if you don’t pass, the teacher is more willing to give you extra points or consider other projects to boost your mark if you made an effort to succeed.
Allah has sent messengers, left written scriptures, people who have believed in him have forever walked this Earth; who has never heard of Islam? He has given us all the tools and reasons to believe, and yet, we shun away.
So when it comes to school, no one sheds a tear for a lazy, unwilling, rebellious student. However, when it comes to the single most important aspect: heaven or hell; everyone is up and arms, revolted at the perspective of ending up in hell.
It is as if Allah has pleasure in punishing mankind. Why would he find pleasure in such treatment; He created us. Therefore, He only asks little of us in return for great reward (heaven).
What would Allah do with your punishment if you are grateful and believe? And ever is Allah Appreciative and Knowing.
Surah An-Nisa (4 – 147)
The bare minimum is belief and gratefulness; faith and recognition; obedience and thankfulness. Two simple aspects that imply a lot but will save you from destruction.