I'm currently agnostic (just b/c there's alot of shit idk) but used to be a "devout" christian and a heliocentric model and the probablitly of a theoretical big bang theory had practically zero bearing on my faith. You can call it mental gymnastics but the bible was rewritten multiple times and is definitely open to interpretation. The whole "earth is 5000 years old" interpretation was likely started to make Christians look dumb.