"O you who have believed, indeed the polytheists are najas (impure)," meaning: filthy.
﴿يَا أَيهَا الَّذِينَ آمَنُوا إِنَّمَا الْمُشْرِكُونَ نَجَسٌ﴾ أَيْ: قذرٌ.