If you dropped formal religion, including Christianity, out of life, what would you get? You would get the same things that you get with the formal religions, except God and guidance. Essentially, there would be a whole lot more corruption, a whole lot more warring, a whole lot more "badness" among people.
I strongly disagree. In those nations where religion holds less sway, we see LESS of the above. See Sweden for a good example. Of course the argument could be made that socialism is itself a formal religion, but you are specifically referring to Christianity and to a lesser extent, other theistic religions.
People who do bad things will use whatever methods they can to do bad things. They will take as much good as they can, and twist it to their own ways, to make it bad. Without the good of the formal religions, things would be a lot worse. If you think that people couldn't or wouldn't design bad things without formal religion, you are extremely naive.
On the contrary, in a rational world bad people do bad things and good people do good things. (I'll get into "good" and "evil" in a moment). With the backing of religion, good people do bad things, and often with a clear conscience. For a number of good examples from within your book, just read the book of Exodus. Granted, most of it is false, like zero evidence that the Hebrews were ever slaves in egypt for instance, but it openly condones putting entire populations to the sword in the name of "The LORD of HOSTS" if you like the KJV, or more correctly translated The God of Armies or Jehovah (medieval latin) or Yahwey as most modern scholars believe the name to be properly pronounced. One of the things commanded by your god was the dashing of babies against the rocks. And do not give me the "sins of the father" argument, because there is NO moral or ethical way to justify it. Which is pretty bad for your religion, because it's the crux of your beliefs. (see what I did there? Crux is short for Crucifix).
Religion offers guidance towards goodness. Even a formally semi-violent religion like Islam offers guidance towards goodness in this life. Think of how bad it would be without religion.
This is a tamer version of what Christians often say to atheists. It scares the shit out of me. Because what you're really saying is that without some religion going on, then people IN GENERAL are going to run rampant, murdering, raping, stealing, and generally being assholes. This tells us a LOT about the religious mindset. Luckily, we have all of history to prove it untrue. If humans were inherently evil, using the term the way religious people do, then no such books would be written, and given that none of the thousands of gods does a fucking thing, even if they were no one would care. Our species would not have survived. For the most part, we do not need to be told that it's wrong to attack and kill our fellow men and women. Crime is actually a pretty low percentage of human activity, once you take away statutory crime. (that's a discussion for another time). And as one would expect without the religious mindset, the worst crimes are the least common. A guy might not think twice about grabbing a loaf of bread, but will think a lot harder about assault or murder, even if he's deviant.
The truth, clearly observable if you have ANY grasp of reality and the ability to think, is that people are generally pretty neutral. We're a social species, so we work out ways to interact with each other. We also are pack animals, so we tend to make codes, such as religion, that make the "outsider" somehow less than human. That is just as egregious as theism, but it's at least something we can recognize and mitigate IN THE ABSENCE of religion. Within the framework of religion, the "other" will always be subhuman. It is not an accident that secularization of the world led to the largest population of humans ever. Civilized men rarely kill because of "god" anymore, with a few glaring exceptions. Unfortunately, those glaring exceptions are good at getting themselves into positions of power (which is a big part of why I'm an anarchist as well as an atheist).
More important, even if there were no badness along with no formal religion, that is, even if people were not mean and bad, period, they would still get old and die. Old age and death seem to be built into the "genetics" of nature. Why do I mention this? Because old age isn't something that is nice and good. It is wicked and evil. It leads to death, and eternal death which includes agony of soul forever.
Religion stands firmly in the way of mitigating death by providing the obvious fairy tale you present below. There is just about zero evidence that anything "survives" death except energy, which is never destroyed. There is a whole lot of evidence that we could extend life indefinitely via technologies that Christians oppose on "principle" because it's "playing god". Well, I for one ain't playing. At base, god means creator, and we are the most creative species we are aware of. In fact, even when I was religious, that bothered me. If we're made in god's image, as Christians and Jews presuppose, then why do Christians stand so heavily AGAINST being creative? (again, this is something of a deviation from the discussion, but something you ought to think about)
The pursuit of immortality predates Christianity by a rather large number of millenia. The ability to pursue it by technical means is just now falling into place, but a lot of that research has been very vocally opposed by Christians. For examples of the works, I suggest you google the methuselah mouse prize, SENS, and Dr. Aubrey DeGrey. It's beyond the scope of this discussion. I've been heavily involved in it for several decades now.
At least the Christian religion shows us the way out of death which would not be known without the formal Christian religion. Without the Bible it would almost be absolutely, formally unknown.
The point? Without the Bible, the way out of death to a joyous life in Heaven would be missed by almost all people. In addition, life and living conditions on earth would be worse. Now, at least, there will be some millions or billions in Heaven.
Utterly false. Every religion that I am aware of deals with "what happens after death" and they all disagree.
Now let me provide a little conundrum for you. Take away all the other contradictions and hypocrisy surrounding all religion and ask yourself this:
Based on the ideation that all theistic religions claim two things:
1. There is an all powerful god that has made or set in motion the entirety of our universe and
2. This god wishes to be worshipped.
The question is, if the above were true, how many religions would exist?
EDIT: I forgot to go into the definition of good and evil. Both are to a large extent religious concepts, but they are derived from very real concepts. So, to a social animal, what is good, and what is evil?
Good would be that which optimizes survival of the species. To a socially aware species, such as ours, this could also extend to what is good for the individual actor WITH REFERENCE to the overall paradigm. If it's optimal for both the individual AND the survival of the species, it could be considered "good". If it is optimal for the individual and inimical to the survival of the species (murder comes to mind) then it would not be. If it is optimal for the individual and does not directly affect the species ("vices" come to mind) then it would be neither.
Evil, in my way of thinking, is that which is inimical to survival of the species WITHIN THE CONTEXT OF HUMAN ACTION (or another hypothetical self aware species). That which is inimical to a species survival outside of that context is not evil, simply dangerous. Evil requires a conscious actor.
Using the above basal axioms, most religions are a mix of good and evil, but because of the unquestionable nature of "faith", the evil triumphs over the good whenever "god" has been assigned some role. Whatever you may think of the sciences, one thing about them makes them superiour to all relgious thought: There is NO forbidden question. Scientific thought operates from the axiom that all things are knowable. Not all things are known, in fact the more we learn the more we find that there is more to learn. But simply that it can be known, if the right questions are asked. In my paradigm (shared by a great many free thinking people), there is no reason to not question ANY axiom. I take it farther than most, in that by the above definitions, I consider refusal to consider a question to be evil.
As a personal "for instance", I find it most egregious that we are not already on other worlds. There is NO technical reason for this, but a lot of emotion, and yes, religious opposition.