Allah says:
"For you is your religion, and for me is my religion."
His statement does not indicate approval of their religion, nor does it indicate acknowledging it as valid.
Rather, it indicates his disavowal of their religion.
For this reason, the Prophet ﷺ said: "Indeed, this surah is a declaration of disavowal from polytheism."
Al-Jawāb al-Ṣaḥīḥ li-man Baddala Dīn al-Masīḥ (6/60)