Yes, ‘Oh my God’ is considered a colloquialism. It is an informal expression commonly used in everyday conversation to convey surprise, shock, or strong emotion.
This phrase has become widely accepted in casual speech and writing, transcending its religious origins. While it may have originally been used in a more serious context, today, it is often used in a light-hearted or even humorous manner.
Colloquialisms, including ‘Oh my God’, often reflect the culture and social norms of a particular group or region. They can provide insight into the emotions or attitudes of speakers and help convey the richness of informal language.