"Why then do they not" [meaning] why do they not "bring upon them a clear authority" [meaning] a clear proof that God has commanded them to worship them. "And who is more unjust than one who invents a lie against God" [meaning] there is no one more unjust than him.
﴿لَوْلَا﴾ هَلَّا ﴿يَأْتُونَ عَلَيْهِمْ بِسُلْطَانٍ بَيِّنٍ﴾ بِحُجَّةٍ بَيِّنَةٍ؛ بِأَنَّ اللَّهَ أَمَرَهُمْ بِعِبَادَتِهِمْ ﴿فَمَنْ أَظْلَمُ مِمَّنِ افْتَرَى على الله كذبا﴾ أَي: لَا أحد أظلم مِنْهُ.