I had a welcome comment the other day from someone who feels it is right to argue that God is a delusion of the human mind. This is very much a Richard Dawkins thing I suspect.
It is often said that there is no scientific proof of God. It is also true to say that there is no scientific way of prooving there is no God. (Interestingly, type into Google the Lennox, Dawkins debate - very interesting).
From my point of view, I see God the creator in all things around us. It is a marvellous thing to behold the beauty of my baby girl who was, without a doubt, "created". That she has come into being and is so perfect is, in the words of my good friend "Major Clanger", just a nonsense. There is no logic that is navigable by man that can persuade me otherwise.
On the other point raised - about Islam and Christianity - it is true to say that many people have been killed in the name of these religions. I would say that this is more due to man's choices about these religions.
Christianity is all about grace and peace. I cannot speak for Islam.