قُلْ إِنَّ الَّذِينَ يَفْتَرُونَ عَلَى اللّهِ الْكَذِبَ لاَ يُفْلِحُونَ
Say: "Verily, those who invent a lie against Allah will never be successful."
Allah warned the liars that fabricated the claim that He has begotten a son. He warned that they will not succeed, never prospering in this world or in the Hereafter. In this world Allah will lead them, step-by-step, to their ruin. He will give them respite and put up with them for a while. He will allow them to have little enjoyment,
ثُمَّ نَضْطَرُّهُمْ إِلَى عَذَابٍ غَلِيظٍ
then in the end We shall oblige them to (enter) a great torment. (31:24)
As Allah said here: