God cannot be proved. Some use this as an excuse to claim, therefore God does not exist. Yet so many things exist that cannot be proved beyond doubt. And perhaps God prefers it that way. The Christian religion places a great deal of importance on "faith." Faith being the a belief in that which is true but lacks evidence.
Some suffering from an over abundance in confidence forget 2 things. 1. Every few years a ton of stuff that we have "proved." is found to be only partially true, untrue, or faked by the "research" team. and 2. God cannot be proved but He cannot be disproved either.
What really interests me is why Atheists get so upset about seeing Christian things and hearing Christian prayers. When hear someone talking about something that I consider to be a fairy tale, I roll my eyes and move on. I don't claim offense, I don't try to have their speech banned, I don't even care if they sing about it in public schools. What I believe is going on here is complex --but in many cases, I think these people (who claim to be offended by everything Christian) really do believe that there is a God (subconsciously, perhaps) and they know that they are acting against His will or they desire to act against His will, and thus they use these behaviours as a defense mechanism. Seriously, if you really didn't believe, how can it be that offensive to you? Hmmmm. Paging Dr. Freud....
My opinion, as a highly educated scientist and a Christian, is that God and religion are not necessarily at odds and those who think they are (from either camp,) are no where near as smart as they think they are.
Along these lines, there was a kid I went to school with that, in 8th grade, claimed he was an atheist (of course the next week he might claim he was Jesus - he was kind of out there). One day in our health class, Mr. Hunt, the very southern gym teacher that was teaching the class, confronted him about his claim. He asked, "Do you ever take the Lord's name in vain? Do you ever say God d*** it?" The kid said, "Well yeah I do." Mr. Hunt's reply was, "Then you're no atheist. If you didn't believe in Him, then why would you even use His name?"