"Do they believe in falsehood?" (stated) as an interrogative; meaning: have they believed in falsehood? And the falsehood is Iblis. "And in the favor of Allah they disbelieve" is like His saying: "Have you not seen those who exchanged the favor of Allah with disbelief?"
﴿أفبالباطل يُؤمنُونَ﴾ عَلَى الاسْتِفْهَامِ؛ أَيْ: قَدْ آمَنُوا بِالْبَاطِلِ، وَالْبَاطُلُ: إِبْلِيسُ ﴿وَبِنِعْمَةِ اللَّهِ هم يكفرون﴾ هُوَ كَقَوْلِهِ: ﴿أَلَمْ تَرَ إِلَى الَّذين بدلُوا نعْمَة الله كفرا﴾.
