First - You have to start first with "Do I believe in God?" Yes or no will put you in one of these 2 categories. Once you believe in God (or don't believe there isn't one), then that's when the next question is asked. This would be the OP's second question. The 1st one needs to be answered first.

Second, this is done with research. Not reading a few tweets, but months/years of research that nobody wants to put time in to. And when one of these "quick people" want an answer and someone who researched it gives their opinion, they're immediately shut down. Research the bible, the different versions of it, etc, and you can trace all variances down to one specific version. Try King James Version. People can pull scripture out all they want to make whatever point they want -- I recommend going back and reading the entire chapter the verses refer to in order to get that all important context that so many people miss.

Third, I'm not sure I agree with you that the scientific method holds no ultimate truths. The Scientific method (used by reproducing results and observing them) can lead to many facts about life; commonly known as "truth." There are many kinds of truth, just like kool-aid. You cannot look for the answers to all truths in one location.

Again, I would recommend any Atheist to check out "100 Reasons why Evolution is so stupid" for some great explanations on definitions of terms; you'll discover that the argument of what to believe in is rooted in everyone not using the same definitions of terms.