1) Imaginations don't "decide" anything, they just are. So part of your point doesn't make much sense, or the language that you've chosen isn't capturing the point well, on this thought.
2) Multiple disconnected cultures from geographic regions separated both by oceans and time have independently created the concept of "God", "Divinity", or "whatever". The particulars of language, details of the characters, myths, legends, et. al. are all colloquial; which supports your point to some degree. However, your point fails to recognize the contrary position that does actually exist - the concept of "God" hasn't "traveled", but rather there is evidence that the idea og "God(s)" are a universal construct created by many cultures, peoples, in different areas and eras.
3)The question posed on "faith" as it pertains to atheism, Christianity, or any other "religion" isn't fairly addressed, imho. All value-systems, belief-systems, world-views, philosophies, credos, et. al. are all based in a fundamental choice that boils down to "what do I as a person place my faith in?" The answer for every person is different. Each person much reconcile their life, their past, their family history, their views, their teachings, their experience and their perceptions and make a choice: faith in science, faith in religion, faith in logical, faith in people, faith in whatever.
I have faith in the Internet because no one ever lies there. (sarcasm alert)