Christians could just as easily be worshipping Ra, Baal, or Anu today

just as chritians could be praising whoever, the same applies to all of humanity.
It all has to do with where you grew up, how you where raised, the person you are/were/will become. Just as with the order in the chaos of nature, of which we all are a part. Some will be firemen and play chess on saturdays. some will be wall street execs, with the hobby of serial killing... does religious choice have any play here? No, I don't believe it does.

The OP is 100% accurate "it was all a matter of politics, wars, kingdoms and chance" but not those points alone. One of the biggest influences having directed all the 'mainstream' religions of ages past, is a humans conscious perspective on morals and values. (here, think of the fear, of even the people before christ, that could have been experienced in this vast world, then, unkown) Now this is something a slight bit worrysome. Most of us know of the brutality in the scripts, but, the texts of all religions can and do hold very meaningfull insights, yet, i believe, only if a contemporary/modern reader of such scripts THINKS about what these mean to this day and age. However, worrysome, because nearly all religions or belief systems claim they are right, there will be altercations.

on another note, a very honest one. personally, my beliefs seem ever affected by information and meditation on what is available. I believe we are all on a spiritual path individually and together.