Can non-Muslims especially the People of the Book enter Paradise? It is believed that it exclusive right of the Muslims to enter God's Paradise.
We believe that God Almighty has sent human beings in this world to test who among them is good in deed. (al-Mulk 67:1) God has made sure that some of the fundamental religious realities are clear to man. For example he implanted in the human nature the awareness of good and evil. He created in them the awareness that there is a God who created this universe. He is just and merciful. The belief in one God is thus part of human orientation.
Before their creation God covenanted with all the humans that they would acknowledge Him as their Lord and would worship Him as the one God. This covenant is not there in the active consciousness of humans. It, however, is there in the recesses of subconscious. That is why man is always looking for a deity to worship. This explains why all the people of the world believe in the God or gods in some ways.
Another important thing is the interaction of the first man with God. Adam interacted with God and then passed on this knowledge to his progeny. The above mentioned fact regarding the ubiquitous awareness of existence of God owes to this knowledge handed down from Adam too.
Third most important thing that leads to existence of God is His providence that covers the entire universe. Those who ponder over the system of the universe and its harmonious working to the fulfillment of a single end despite difference and opposition in various phenomena can understand that it has a purpose and it has a creator.
These things make it incumbent upon man to believe in one God and worship Him. He will be held accountable for failing to do so. Everybody will be questioned on the Last day in this regard. However, people will be, justice demands, given fair trial. God knows the secrets of hearts. He can understand who rejected Him knowingly and who was not able to grasp the reality owing to different factors.
We believe that everyone is answerable before God regarding his stance on existence of God and following moral values which are universal. Belief in the afterlife and prophethood are a corollary of belief in the unicity of God. Many people did not even heard of Messengers. Many believe and are intellectually convinced that the earlier Messengers were the true ones. They therefore believe on their respective Messengers.
All such cases will be considered individually. And we cannot declare that all non-Muslims or followers of other faiths will necessarily go to Hell. We only say that Islam is the last and the true religion of God. It is incumbent upon the people to ponder over its teachings and decide to accept or reject it on the basis of arguments. Still, however, there could be people who are not convinced of its veracity for many reasons. God will accept their excuse if found valid. Nothing is hidden from God. Nobody can deceive him.
Thus the basis thing is the belief in one God. Other beliefs come under it and are secondary in nature. God has clearly stated that those who followed other religions including Judaism, Christianity and others truly and did good deeds will be rewarded. He has also made it clear that He would not forgive polytheism. Any other sin He may forgive.
إِنَّ اللّهَ لاَ يَغْفِرُ أَن يُشْرَكَ بِهِ وَيَغْفِرُ مَا دُونَ ذَلِكَ لِمَن يَشَاء وَمَن يُشْرِكْ بِاللّهِ فَقَدِ افْتَرَى إِثْمًا عَظِيمًا
Allah is not going to forgive that partners should be set up with Him; but He forgives anything else, to whom He pleases; to set up partners with Allah is to devise a sin most heinous indeed. (4:48)
Debate with those of the non-Muslims who believe in the existence of one God namely the monotheists will be different from the ones who believe in cause and effect to be the primal origin of the world and its running. With the latter we need first to argue that actually there exists an entity, which effectively runs the universe and cause and effect is primarily controlled by him.
Also it is not enough to be born Muslim rather everyone needs to analyze the creed he is born in. If one is guided to monotheism and is convinced of the creed he adheres to this puts him under a huge responsibility. He is under a harder test than those who did not have an opportunity to be acquainted to the religion in that better and is not convinced of veracity of Islam or any other monotheistic religion. Those who do not believe in God and have never been invited to Islam in a convincing way cannot be declared to be worthy of Hell. God only holds accountable those who reject the truth knowingly. Therefore, we believe that those of the non-Muslims who were never convinced of the veracity of Islam will be judged on the innate guidance provided to them. Such person may or may not be forgiven. If such a person sticks to the truth and behave accordingly we hope that he will be forgiven by the most merciful if his excuse is found acceptable.
We should always try to politely invite those of the non-Muslims to Islam whom we know if the circumstances allow us. We need to present all the arguments wisely rather than declaring them condemned to hell, which will necessarily drive them away from what we are inviting them to. Of course they will be questioned whether they heard about Muhammad (sws) and his message and why did they fail to study his message and accept it after due consideration. But we cannot hold that they are always to put to Hell.
Likewise it is not very likely that all the Muslims go to the Paradise. I believe that they had to be more strictly judged before being rewarded with Jannah. The Holy Qur'an repeatedly declares that merely being among a religious group or family does not render one worthy of paradise. Therefore, we need to be on guard and not to waste our lives on false hope of being redeemed by virtue of being a born Muslim. We need to continue analyzing our faith and its basis, our acts and their implications.