Qui bono si Deum esse?

I have lately been contemplating a question about God and God's existence. I have not been contemplating whether or not God exists, but rather whether or not it matters if God exists. This train of though has been fueled by my constant interaction with Agnostics/Atheists as well as reflections on Pascal, Feuerbach, Heidegger and Dostoevsky.
To begin with, one must first understand how exactly this question is different than "Does God exist?" For starters, this question is not changed by the actual answer to that question, but the answer that we personally give this question does affect whether or not we think that it matters. Secondly, this question is a much more advanced one than the previous, and if one contemplates the latter rather than the former, he will achieve a greater understanding of not only human nature, but also the mechanics of religion, philosophy, and especially ethics.
To answer the question, we must ask what many cultured critics of our time have come near, but few have ever really grasped. We must ask the merits of the current system of beliefs across the globe and what would be the alternate (ie, if religions and philosophies of today were non-existent, what would be the effect?). Many critics proclaim boldly that religion is a blight and that humanity would be much better without it. Many state that religions provide faulty ethics and a faulty reasoning for accomplishing ethics. Many attribute the majority of conflicts to religious differences. So, to ask whether it matters if there is a God is to directly focus on these accusations and the overall consequences of siding one way or another.
Let us first remember that religions have been around for a very long time. Where there have not been "religions," there have been philosophies. This is still true today. The men and women who decry organized religion often ally themselves with some form of a philosophy, though we often don't recognize it since they are not preaching in the agora. Thus, they are still holding onto a set of beliefs. However, rather than asserting divine knowledge they assert some other principle, logic, for example, or scientific discovery, or simple observation or something else. Often, these people fail in similar ways to the fundamentalists and extremists of religion, and don't quite follow the tenets of their beliefs, but this will be addressed later.
As far as ethics go, one has to realize that our sense of ethics is, very much, derived from our culture and our religions and philosophies. In fact, to attack religion full on for it's ethics causes a logical contradiction. For most people who condemn the ethics of religions must take a morally relativistic stance, considering by their own words they don't stand behind a specific creed or guided set of principles, yet in this same stance, they cannot take a position against such sets of principles without betraying the single ethical idea of relativism, namely that nothing is wrong. However, it is also the case that to attack religion for its use of eschatology as a way to moderate ethics is also to take a stance more on religion's turf than one realizes. For the idea that "virtue ought to be done for the sake of virtue" is an Aristotelian idea, an idea which in the West was translated by one St Thomas Aquinas, patron saint of philosophers, theologians, universities and students. Even its promulgation today was a result of Catholic scholars in the early twentieth century returning to Thomistic Philosophy. Thus, even in condemning religion for eschatology, critics must borrow from religion to do this.
To think of all conflicts as arising from religion is plain ignorant. I have stated my reasons for thinking this way before, and to save space, I will simply state that many conflicts, especially wars in the previous 300 years, have had no religious component whatsoever, and those which did, were wars that were specifically twisted in order to appeal to the religious of an area. Wars have been fought for millenia.
So now that I've addressed several criticisms against the idea of the existence of God, or at least religion, I shall try to answer the main question of this post. It seems to me that it does not matter whether or not God exists. For if God truly does exist, then a lot of people have been right about a lot of different things. However, if God does not truly exist, then our sense of ethics, our ideas of compassion, etc, are pointless and nullified since it all amounts to nothing in the end, yet it still provides those who live religious lives a sense of fulfillment and happiness. Nietzsche said that Christian ethics were made up and derived, but he admired how effectively they worked, even so much that "the great politicians of Germany, brutes and terrible men, call themselves Christian." Feurbach himself saw that Christianity, though he had no faith in it, provided a means for relieving alienation that people feel, a way to feel real love and give us an ultimate example in Jesus for us to follow. Heidegger saw the lack of faith that humanity was experiencing and the consequent loss of humanity and famously said (as I have quoted multiple times) "Only a god can save us."
Though Pascal often gets a bad reputation from cultured critics, and is highly misinterpreted even among theists, his so-called "wager" lays out a fairly summary argument for the case. If there is a God, then righteous and virtuous behavior (and most certainly belief) can only do one good in the hereafter. If there is no God, and we cease to exist with death, then Christian living can do no harm to us.
Of course, Pascal was a notorious Jansenist who believed God would be angry at sinners. The average Christian, and especially Catholic, of today would not share the same sentiments as Blaise Pascal. Furthermore, the issue is even further complicated with globalization and the knowledge of other religions and their doctrines, practices and ethics. This, however, is a much different question from whether or not God exists, as well as whether it matters. The reality is that living a life that is truly in line with what one's faith teaches them is not only good in the sense of Christian and most modern understanding of good, but is also the easiest way to promote peace and unity.