Non-Muslims Using Islamic Phrases

I have seen multiple instances of non-Muslims using common Islamic phrases, such as: - Alhamdulillah (ٱلْحَمْدُ لِلَّٰهِ) - Inshallah (إن شاء الله) - Mashallah (مَا شَاءَ ٱللَّٰهُ) Where Muslims have complained stating that, "Non-Muslims cannot use Islamic phrases." It seems quite curious, does implementation of in-group terminology not signal some type of positive *endorsement* or *acknowledgement*? Can non-Muslims really not use this terminology? Even if with sincerity?