وَمَا تَفَرَّقُوا إِلاَّ مِن بَعْدِ مَا جَاءهُمُ الْعِلْمُAnd they divided not till after knowledge had come to them,means, their opposition to the truth arose after it had come to them and proof had been established against them. Nothing made them resist in this manner except their transgression and stubbornness.بَغْيًا بَيْنَهُمْوَلَوْلَا كَلِمَةٌ سَبَقَتْ مِن رَّبِّكَ إِلَى أَجَلٍ مُّسَمًّىAnd had it not been for a Word that went forth before from your Lord for an appointed term,means, were it not for the fact that Allah had already decreed that He would delay the reckoning of His servants until the Day of Resurrection, the punishment would have been hastened for them in this world.لَّقُضِيَ بَيْنَهُمْthe matter would have been settled between them.وَإِنَّ الَّذِينَ أُورِثُوا الْكِتَابَ مِن بَعْدِهِمْAnd verily, those who were made to inherit the Scripture after them,means, the later generation which came after the earlier generation which had rejected the truth.لَفِي شَكٍّ مِّنْهُ مُرِيبٍare in grave doubt concerning it.means, they do not have any firm conviction in matters of religion; they merely imitate their forefathers, without any evidence or proof. So they are very confused and doubtful