Can I Obey What Allah Said in Sura 5:47?

Muslims, are we supposed to believe what Allah says in the Quran or not? Do you believe the Quran?

I ask because of this ayah:

Surah 5:47
“Let the People of the Gospel judge by that which Allah hath revealed therein. Whoso judgeth not by that which Allah hath revealed: such are evil-livers.”

Allah says we Christians are supposed to judge by the Gospel. Am I allowed to obey this verse?

But