Be it a hindu religion or christianity, we all believe in the existence of one greatest power above all which is controlling us. But why this debate about his existence? Even if God exists, is he important to our lives, or if he doesn't exists, does it makes any difference??
Sometimes our faith, in God or in anything else, makes our hopes strong. During the bad phase of life, one gets the feeling of optimism that this is not going to be like this forever, thinking that its because of karmas and hopes for some miracle to happen. Even if no miracle happens, we are escorted to good phases in the meanwhile. Its good to rely on somebody other than you, atleast it lowers the burden when you are low. This faith in God also helps us in becoming a better person. Because of the fear of being paid off for our karmas, most of the times we get rescued from harming others by our words or actions..
An atheist may probably reject this theory but a theist and confused atheist would surely agree to it in some way.When we say that this life is all about science, and our existence is based on theory of evolution. And we are formed with the fusion of microbes. That Fusion is a miracle.
When we say all these planets moving around the sun on their regular paths is due to gravitational force of sun, than that gravitational force too is a miracle.. We take births, we die, flowers blossom, fishes swim, birds fly, so many starsin the sky, somewhere its all sea and somewhere its all mountains, infinite galaxies everything seems to be the miracle. This miracle must have been done by someone. And we have named that someone as God. There are so many instances we heard about rebirths and life after death that certainly its a mystery that even science would like to solve.. And untill science solves it or rather discovers some logic behind our bare souls, lets keep guessing the God. But in the end we should not forget science is a miracle too.. :)