Allah said, if they, the disbelievers among the People of the Book and other disbelievers, believe in all of Allah's Books and Messengers and do not differentiate between any of them,

فَقَدِ اهْتَدَواْ

(then they are rightly guided) meaning, they would acquire the truth and be directed to it.

The definition of ` Iman ایمان

From the beginning of the Surah Ai-Baqarah upto this place, different verses have been explaining the nature and essence 'Iman ایمان (faith), sometimes succinctly and sometimes in detail. Verse 137 defines 'Iman ایمان in a simple and short phrase which is at the same time so comprehensive that all possible details and explanations are inherent in it. The earlier verses having established that the only religion which is valid at present is Islam, this verse assures the Muslims that the Jews and the Christians can find the guidance only "if they believe just as you believe", or, in other words, "if they believe in what you believe in." The immediate addressees of the phrase "you believe" are the Holy Prophet ﷺ and his blessed Companions. Thus, in doctrinal matters above all, their 'Iman ایمان has been placed before us as a model, and the verse is essentially a divine commandment, laying down the fundamental principle that the only 'Iman ایمان acceptable to Allah is the one which was adopted by the Holy Prophet ﷺ and his blessed Companions, and that any doctrines or beliefs that deviate from it in the least are neither valid nor acceptable to Allah. That is to say, one should believe in Allah and His attributes, in the angels, in the Books of Allah, in the messengers and prophets of Allah and in their teachings exactly in the same manner as the Holy Prophet ﷺ and the blessed Companions did, without adding or subtracting anything on one's own part and without advancing one's own interpretations or distorting the authentic meanings of the doctrines. Nor is one allowed to assign to the angels or the prophets a station higher or lower than the one assigned to them by the word or deed of the Holy Prophet ﷺ . Moreover, one is also required to be sincere and pure in one's faith, for the contrary would amount to hypocrisy (Nifaq نفاق ).