Word by Word Analysis

وَمَا كَانَ ٱلنَّاسُ إِلَّآ أُمَّةً وَٰحِدَةً فَٱخْتَلَفُوا۟ ۚ وَلَوْلَا كَلِمَةٌ سَبَقَتْ مِن رَّبِّكَ لَقُضِىَ بَيْنَهُمْ فِيمَا فِيهِ يَخْتَلِفُونَ 19

And mankind was not but one community [united in religion], but [then] they differed. And if not for a word that preceded from your Lord, it would have been judged between them [immediately] concerning that over which they differ.