In matters of faith, 1 He has ordained for you that which He had enjoined upon Noah - and into which We gave thee [O Muhammad] insight through revelation 2 - as well as that which We had enjoined upon Abraham, and Moses, and Jesus: Steadfastly uphold the [true] faith, and do not break up your unity therein. 3 [And even though] that [unity of faith] to which thou callest them appears oppressive to those who are wont to ascribe to other beings or forces a share in His divinity, God draws unto Himself everyone who is willing, and guides unto Himself everyone who turns unto Him [Translation of Surah al-Shura, 42 Ayah 13].
1: See first paragraph of note  on 2:256 of Asad Translation. Since, as the sequence shows, the term din cannot apply in this context to "religion" in its widest connotation, including religious laws - which, by their very nature, have been different in each successive dispensation (cf. note  on 5:48 of Asad Translation) - it obviously denotes here only the ethical and spiritual contents of religion, i.e., "faith" in its most general sense. With this verse, the discourse returns to the theme sounded at the beginning of this surah, namely, the unchanging sameness of the spiritual and moral principles underlying all revealed religions.
2: Lit., "which We have revealed unto thee", implying that it was only through revelation that the Prophet Muhammad came to know "that which God had enjoined upon Noah".
3: Cf. 3:19 - "the only [true] religion in the sight of God is [man's] self-surrender unto Him"; and 3:85 - "if one goes in search of a religion other than self-surrender unto God, it will never be accepted from him". Parallel with this principle, enunciated by all of God's apostles, is the categorical statement in 21:92 and 23:52 - "Verily, [O you who believe in Me,] this community of yours is one single community, since I am the Sustainer of you all". Most of the great commentators (e.g., Zamakhshari, Razi, Ibn Kathir) understand this as an unequivocal reference to the ecumenical unity of all religions based on belief in the One God, notwithstanding all the differences with regard to "the [specific] statutes and practices enjoined for the benefit of the various communities in accordance with their [time-bound] conditions ('ala hasab ahwaliha)", as expressed by Zamakhshari in his comments on the verse under discussion.