Surah Al-Hajj (22) — Ayah 17

17. Surely those who believe [16], and those who are Jews [17], and the Sabians [18], and the Christians [19], and the Magians [20], and those who associate partners with Allah [21]—Allah will judge between them on the Day of Resurrection [22]. Surely Allah is Witness over all things.

[16] That is, to have faith in any Messenger of Allah, because the fundamentals of religion for all the Prophets and Messengers have always been the same. (For details, please refer to the footnotes of verses 92 and 93 of this Surah.) In this sense, those who believed in every Prophet were Muslims, and the only difference between Islam and Iman is that Islam is related to outward actions, while Iman is related to the heart. The more one obeys Allah and His Messenger, the stronger the faith becomes, and as faith becomes stronger, one is granted further ability to obey. Thus, Islam and Iman are interconnected and mutually supportive of each other.
[17]
Which Sect Among the Children of Israel Was Called Jews:

Those who believed in Musa (Moses) ؑ were also Muslims and belonged to the nation of Bani Israel. During the lifetime of Musa ؑ, they were not called Jews. They were called Jews when their religion became mixed with their own invented beliefs and they even altered the Book of Allah. According to some, their name is attributed to Yehuda, the eldest son of Yaqub (Jacob) ؑ. However, this explanation does not seem correct for two reasons: first, in this sense, Jews could be called a tribe, not a religion, whereas Jew is the name of a religion, not a tribe; and second, in this sense, all the Children of Israel are included among the Jews, not just the descendants of Yehuda. According to some scholars, the Children of Israel were called Bani Israel until the time of Isa (Jesus) ؑ. Later, in contrast to the Christians, they came to be called Jews.
[18]
Who Are the Sabeans?

The Sabeans were actually a nation of star and sun worshippers who, in defense of their deities, threw Ibrahim (Abraham) ؑ into the fire. These people claimed to be followers of Nuh (Noah) ؑ and denied all the Prophets who came after him. Later, the word "Saba" began to be used in the sense of changing one's religion or turning away from the ancestral faith, and it became a term of abuse. Thus, the polytheists of Makkah also used to "honor" those who accepted Islam with this term, saying that such-and-such a person has become a Sabean, meaning he has become irreligious and faithless. Just as in India, those who turn towards monotheism are labeled as Wahhabis.
[19]
Different Names of Christians:

The followers of Sayyiduna Isa (Jesus) ؑ and the book revealed to him, the Gospel. Initially, their name was Nasiri or Galilean. Isa ؑ was born in Nasirah, a district of Galilee. Thus, the Jews, considering them a sect of innovation, used to call them Nasiri or Galilean. In the Quran, their name is Nasara, and this too can be attributed to Nasirah. Another explanation is that the followers or disciples of Isa ؑ had affirmed ﴿نَحْنُ اَنْصَار اللّٰهِ﴾ [52: 3]. Therefore, these people were called Nasara. Later, they preferred the title "Christian" for themselves. These people also later included many invented beliefs, such as the doctrine of Trinity, the divinity of Christ, and the atonement of Christ, etc.
[20]
Introduction to the Magians:

The Magians were also fire-worshippers and star-worshippers, and like the Sabean sect, claimed to be followers of Nuh (Noah) ؑ and denied the rest of the Prophets. According to them, the gods of good and evil are separate. The god or creator of good is Yazdan, and the god or creator of evil is Ahriman. They call their revealed books Zend and Sata. Mazdak had badly distorted their religion and morals, to the extent that even marriage with one's real sister was declared permissible among them.
[21] By "polytheist" is meant the polytheists of Makkah and the polytheists of other countries, who are not associated with any of the above-mentioned groups. Although, except for the monotheistic Muslims, some form of polytheism is found in all the above religions.
[22] This does not mean that before the Day of Judgment we cannot know where the differences have occurred and to what extent a sect is upon the truth, because the fundamentals of religion have always remained the same and are mentioned in all revealed books, even though the Torah and the Gospel or the Bible have been altered. Still, the fundamentals of religion can be traced, and it can be determined which belief of a sect is correct and which is false. However, in this world, no sect is willing to accept the truth due to religious prejudice. Therefore, on the Day of Judgment, Allah Himself will not only decide these matters but will also enforce that decision.