Whether the OP is a Christian or not doesn't matter, does it? Will you acknowledge the contradictions in the Bible? It's a subject worth discussing.
OK. Fair enough.
Yes. Obviously the bible is rife with contradictions. Thats being said I also know that some contradictions were designed to make the reader think as when the children of Adam went to find a mate in a city which should compel the reader to reconsider the subject of being formed by God and becoming a living being as being not about the creation of the body or the first human being.
Other instances are obvious redactions as when someone put on the end of a letter of Paul "submit to the authority of Caesar" who happened to be Nero at the time..
This contradicts the teaching of Jesus on every level and the motive of the unknown editors is not mysterious at all.
So how do YOU decide which parts to believe?
I use my knowledge of literary expressions, figurative language, homonyms, parables, metaphors, analogies, hyperbole, etc, along with scientific facts about the nature of reality as constraints in discerning the teaching.
In my thinking, whether or not the dead ever came out of their graves was never a question of faith or subject of belief. I simply ask myself , "what is the author trying to say." I see that belief without understanding is a curse.
Once superstition is dismissed and if the reader has at least a second grade reading level, the intended meaning almost always becomes clear.
For more sensitive subjects an additional effort is required.
Its really not that hard. Its a matter of logical deduction.
Anyone can do it anytime, anywhere.
You can even do it in secret.