For your convenience, I will paste the answer here again, but ya, please do look at the thread for a detailed analysis about it amongst our members. This is just a very short answer.
This is a very big discussion.
I will say in short.
Many people think Islam is a new religion and Prophet Muhammad PBUH is the founder of this religion. This is not true.
Islam is not a new religion.
Islam existed since time immemorial, since men set foot on the Earth.
Islam comes from the root Arabic word Salam, which means Peace. It also comes from the word Silm which means "submitting your will to God". As a whole, Islam means "peace acquired by submitting your will to God". Any human being who submits his will to God, in Arabic we call as Muslim.
But the point to note here is, God sent different Prophets and Messengers with revelations from time to time, to let people know there is 1 God. Since God didn't find it fit to preserve those scriptures, hence those scriptures were meant for a particular group of people and was meant to be followed for a particular time period. Allah says that "He sent a revelation in every age", and "there's not a single nation to whom He has not sent a Messenger".
But like I said, since God didn't find it fit to preserve them, hence those revelations and laws were meant for a certain group of people and was meant to be followed till a certain time period.
The last and final revelation however is the Quran, and the last and final Messenger is Prophet Muhammad PBUH. Since he is the last messenger and the Quran is the last revelation, so there's no more messenger or revelation to come again. Prophet Muhammad PBUH is hence not only sent for the Muslims or the Arabs, but the whole of humanity and the Quran isn't only for the Muslims, it's for the whole of humanity and is meant to be followed for eternity. Allah clearly says in the Quran that He completed the religion for us and have chosen for humankind Islam as a religion, nothing new can be added, nothing can be subtracted.
So we understand that today, Islam is the only religion that is to be followed.
The verse you mentioned speaks of the people of that time, at those times those who followed their messenger and teachings, they will go to Paradise. Because their law was meant for them and for a particular time period. Hence THOSE people, at THAT time, who followed the teachings of the messenger, correct teachings, they will go to Paradise. But today it's the time of last revelation, Quran, so one can only go to Paradise by following the Quran and Sunnah, not otherwise. What you mentioned is for the past, those people, that time, not us or this time, hope this helps.
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