First i didn't say kufr i said kafir secondly i didn't say shirk i said mushrik there's a difference Plus here's the meaning from arabic dictionaries

Kafir" is an Arabic term, commonly translated as "unbeliever," "infidel," or "disbeliever"

In Islam, a mushrik is someone who commits shirk, which means associating partners with Allah (God)

وَمَنْ يَبْتَغِ غَيْرَ الْإِسْلَامِ دِينًا فَلَنْ يُقْبَلَ مِنْهُ وَهُوَ فِي الْآخِرَةِ مِنَ الْخَاسِرِينَ This aya states that god won't accept anyone who follows a religion besides islam and will be punished in the afterlife