Christians: If the God who punished people by infanticide is the same "unchanged" guy who...?

Thats what the fundies believe -- "god never changes." Then you point out the obvious changes (eating shellfish, not wearing linen) and they say some nonsense about the "old laws" that changed. So then you say "Okay then, your 'god' does change!" and they still claim he doesn't. Round and round in circles with their fundie logic...