Believing in Billions of years doesn't make you a non Christian, it just makes you wrong. Many different denominations have varying beliefs. They are still Christians. We won't know for sure until we die, but the evidence for a young earth is in the bible and in science.
There are many Christian scientists (small “s”, not the denomination, but actual scientists). They dispute the secular scientist's views. Science first needs to be defined. What qualifies as science these days is a joke. I like double blind studies and actual FACTS, instead of “theories”. Much of so called science today is nothing but theory and computer models.
You might find this informative:
So, there's no such thing as billions of years? The entire universal expanse of space-time just came into being 6000 years ago, all for the convenience of us, centered here on Earth?
How old is God then? Did God come into being just before 6000 years ago, or has God "always been" so to speak, meaning God has been in existence forever which is WAY more than 6000 years ago. What about before that? Why would God erase all evidence of the history of the universe prior to 6000 years ago, making the concept of "billions of years" in the past "wrong?"