For the entire existence of mankind, we have found the need to put some meaning on life and whether or not anything lies beyond the grave. Yet many people fail to realize that we humans came up with a meaning when there otherwise is none. "If there were no God, it would become necessary for mankind to invent one" (Voltaire). I believe Voltaire is saying how we as humans always try to find answers for life's unanswerable questions. When we view god we ask the questions who is God? Where is it? How it works? To all this the answer is "I don't know". Voltaire is saying is that humanity needs God. Even if we try to eradicate the concept of God and wipe out every other sacred text book mentioning about it, we will find that humans will invent it again. . As we have learned and expanded our knowledge we have molded our God(s) to fit our needs. The ancient Greeks and Romans thought gods pulled the sun across the sky; we found out that this was from the earth orbiting around the sun and now we no longer have those gods. If god were not man made we would not see so many different ones whether it be Buddhism, Christianity etc. .
God is the most important invention of the human race. It's the result of our incapacity to envision a meaning for our finite lifespan other than to conserve itself in another realm of time and space. It's a very good coping mechanism. I think all of us want there to be an afterlife, if we could have one wish it would to be the guarantee that there is an one. It's incredibly depressing that there could be no life after death and that maybe we just return to the void that was there from when before we were born. I can see why people would turn to religion and why humans made a higher being to tell us how to live and to give us a sort of meaning in life. In the end It's just human arrogance driven by ego to believe that "human existence" is anything other than just another occurrence in the large spectrum of the Universe and Earth.