Can belief in God be rational?

You clearly failed to addressed the point i made about causality and how something cannot come from nothing. If youre speaking from a scientific perspective nothing can be absolute you can only have evidence towards it but we were discussing about rationality and reasoning. So my point was its IRRATIONAL to believe particles etc came from nothing. You need an ultimate cause to start something and again there isnt anything 100% nothing is but using logic and rationality based off what i said its rational to believe god exists

a + b doesn't have to be 3 unfortunately. If you believe Christianity then you also have to believe in Satanism by the same logic, you can't pick and choose how the universe is. Just because you believe it doesn't make it true. I'm sorry :'(

This is what any religious argument reminds me of.

People also believed the world was flat until a few hundred years ago, would that belief also be rational with todays evidence?

Yes, there's a whole lead of philosophical literature on this; read Plantinga's Warranted Christian Belief for an example.

http://www.iep.utm.edu/faith-re/
http://plato.stanford.edu/entries/faith/

are all useful too