Surah 22. Al-Hajj, Ayah 71

I.e., through independent reasoning or observation.

I.e., despite their awareness that God alone knows all and is, therefore, unique in His all-embracing Presence.

See surah {3}, note [106].

When plain common-sense shows the absurdity of false worship, behind which there is neither knowledge, intelligence, nor authority (quite the contrary), who or what can help the false misguided creatures who dishonour Allah by false worship?