Tafsir of Ash-Shura 42:8

{ لَجَعَلَهُمْ أُمَّةً وَاحِدَةً } "He would have made them one community," meaning: all of them believers, through compulsion and coercion. This is like His saying—Exalted is He—: "And if We had willed, We could have given every soul its guidance" (As-Sajdah: 13), and His saying: "And had your Lord willed, those on earth would have believed, all of them entirely" (Yunus: 99).

The Evidence The evidence that the meaning here is "compulsion toward belief" is His saying: "Then, [O Muhammad], would you compel the people in order that they become believers?" (Yunus: 99). The placement of the interrogative hamza of denial upon the one being compelled, rather than upon the act of compulsion itself, is proof that Allah alone is capable of this compulsion, and no one else.

The Meaning The meaning is: If your Lord had willed with a "will of power," He would have forced them all to believe. However, He willed with a "will of wisdom," so He burdened them with obligations and based their affairs upon what they choose, so that He may admit those who believe into His mercy. They are the ones intended by "whom He wills." Do you not see their placement in contrast to the wrongdoers? He leaves the wrongdoers without a protector or a helper in His punishment.

{ أَمِ اتَّخَذُوا مِن دُونِهِ أَوْلِيَاءَ ۖ فَاللَّهُ هُوَ الْوَلِيُّ وَهُوَ يُحْيِي الْمَوْتَىٰ وَهُوَ عَلَىٰ كُلِّ شَيْءٍ قَدِيرٌ } "Or have they taken protectors besides Him? But Allah—He is the Protector, and He gives life to the dead, and He is over all things competent."