Personal opinion? Religion was created by men to explain things that other men did not understand. These men disguised their lack of understanding as gods and demons. For example, let's look at crops. Crops not growing? It was the work of the devil. Crops plentiful? It was God's blessing. Back before these folks knew of weather patterns, soil composition, growing seasons, photosynthesis, and other scientific doohickeys that explain why crops grow, the only way they could explain why their crops grew or didn't grow at all was through these higher beings. I believe that this is the basis of religion, men trying to explain things that they themselves do not understand. Being that many folks had their own ideas about which gods were responsible for what, the basis of all modern religions were founded through ignorance and lack of understanding. Know-it-alls with an agenda. I'm aware that this is probaby very wrong, being that I don't know a lot about the origin of each religion. I'm simply using a blanket statement to share my thoughts.
Religion exists today because there is no absolute truth to what is and what isn't. We have a lot of really solid ideas, but no absolute. There is no absolute to where man comes from, there is no absolute to where the Universe came from, there is no absolute to where we are going...there's simply ideas and theories. Religion, born out of ignornace and lack of knowledge, continues to thrive because there is still no knowledge. People rely on faith in a being that may or may not exist to give them meaning in their lives, to give them guidence and care when they need it and to give them comfort when everything goes wrong.
Now I want to make myself very clear when I say that I believe that people should be allowed to practice whatever faith they like. I make no judgements on anyone's character or otherwise based solely on what they think. I do not persecute and I do not look down on those that feel differently than I do. What you are about to read is my personal belief on the subject of God vs. No-God.
I, personally, have never seen an instance where a higher being has influenced life as we know it. I am full-blown agnostic. I do not know for a fact if their is a higher being responsible for this mess we call a world. I do not know for a fact that there is not a higher being responsible for this mess we call a world. But, at the same time, I don't care one way or the other. Knowing for a fact one way or another is not going to change my outlook on life, nor will it change how I live. Knowing the origin of the Universe and Man will not change how I live or act. I do not actively seek knowledge in matters such as these because I do not find them important to me. I'm more concerned with living my life, day by day, than I am with knowing if there is a God or not. My philosophy, in a nutshell, is "I'll let you believe what you want if you won't try to get me to believe it, too."
When I know, for a fact, that a God does or does not exist, I'll make my decision from there whether or not I want to believe in Him. Right now, since I do not know, I am not sure one way or another. I have no religion, and I don't care to have one.