God is at best a delusion, "...Psychiatry. a fixed false belief that is resistant to reason or confrontation with actual fact...".
Faith of the religious type tends to run counter to, and in many cases seeks to undermine, reason.
Religion itself evolved as a system of managing finite resources. When humans became agrarian they needed different rules for some simple reasons:
1.) People could no longer just deplete the area and move on like hunter-gatherers.
2.) The increase of population of agrarian living meant that the concrete interconnectivity of the social unit had to be replaced with an abstract interconnectivity (it is easier to understand "don't steal from your fellow [insert affiliation here], than it is to understand don't steal from Bob the baker, Carl the cobbler, Joe the cowherd, Mark the smith, etc...). In a necessarily small group of hunter-gatherers you wouldn't steal because you knew everybody and unless you had an aberrant psyche understood that that would weaken the group. Growing populations meant that you didn't necessarily know everybody and that visceral knowledge of the damage you would cause was diluted by you lack of direct connection to your would be victim.
3.) The wise person/elder/keeper of lore of the group could no longer directly interact with everyone. This means you needed more of those types of people, but at the same time you need to give consistent information so the wise ones necessarily codified their wisdom so that they wouldn't contradict each other and to leave a legacy of knowledge.
Religions are a combination of government and science. Government in that it sets rules and provides logistics for the distribution of goods. Science in that it attempts to explain the 'whys'.
By and large people have realized that religion as government is outmoded and unwieldy. (e.g. Protestant Reformation, birth of the Anglican church, the fact the primary architects of the most modern form of government [ours - I know crazy, right] were Deists (the 18th century's version of Atheists and to some extent Agnostics, the fact that it took until the 20th century for the Vatican to apologize for torturing and murdering scientists [who were correct!] during the Renaissance).
However, people have an amazing (to me) problem realizing that religion as science is even more outmoded and unwieldy. What religion invented ANYTHING in the last 200 years (you know the horse transportation to rocket/jet turbine/mag-lev era) that possibly competes with the importance of the microchip, antibiotics, sterilized surgery, fiber-optics, etc...
Religion isn't the best government you can have, it isn't the best science you can have. Why do people still use it? Oh yeah, it makes them feel better. So do drugs, and they are currently illegal, or controlled due to their destructive side effects. What destructive side effects could religion possibly have? Surely not the:
4.) Ongoing wars or militarily sustained truces in: Northern Ireland
5.) Murder of OB/GYNs
6.) Male and female circumcision (and other mutilation)
But what about gunpowder and nuclear weapons, science made those, right? Yes, but science never said to use them. Religions motivate people to kill people, usually with very explicit rules for doing so in their respective canons. Can you find an Einstein (or anyone who worked on the Manhattan project) quote that say we should bomb population X? Didn't think so.
Is science or are scientists perfect? No. They're humans pursuing human activity, the difference is that their whims and opinions aren't blindly followed by masses of people who haven't stopped shopping long enough to wonder why they do or believe what they do or believe.