“Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important.”

Simplified Meaning:

Christianity deals with very big questions about life and what happens after we die. If what it teaches isn't true, it doesn't really matter. It's like a story that isn't real; it doesn't change anything about what's actually happening in the world. But if what Christianity says is true, then it changes everything. It's like finding out you have a treasure map that leads to real treasure. The idea is that something this important can't just be "kind of" important. For example, think about how we treat fire: it's either really important because it can help cook food and keep us warm, or it's dangerous and can burn things down; we never treat a fire like it's just an okay thing. In a similar way, people should think carefully about their beliefs and what they mean for their lives, rather than ignoring them or treating them as just another thing on their to-do list.