﴿ وَٱلَّذِينَ كَفَرُوا۟ بَعْضُهُمْ أَوْلِيَآءُ بَعْضٍ ۚ إِلَّا تَفْعَلُوهُ تَكُن فِتْنَةٌۭ فِى ٱلْأَرْضِ وَفَسَادٌۭ كَبِيرٌۭ ﴾

“With all this, [remember that] those who are bent on denying the truth are allies of one another; and unless you act likewise [among yourselves], oppression will reign on earth, and great corruption.”

And those who disbelieve are allies of one another in terms of mutual support and inheritance and so there is no inheriting between you and them. Unless you do this unless you ally yourselves with the believers and sever relations with the disbelievers there will be sedition in the land and great corruption with disbelief gaining power and Islam becoming weak.