Baremission, you are of course entitled to believe what you wish and anyone and everyone should respect that. My query is, that since your are asking for proof of the existence of God, that you are merely a sceptic and not quite an atheist, although this can be called weak atheism. To be a true atheist, as far as I understood, one would need to assert an explicitly held belief that God does not nor cannot exist.
It is simply a matter of degrees, but there is a difference between the strong and weak atheist, and some falling by the wayside even call themselves agnostic. Disbelieving in God is not the same as believing he/she doesn�t exist. If you feel that we do not know for sure whether God exists then you are probably agnostic. One theory is that without God atheism wouldn�t exist, so therefore to be an atheist there must be a god for you not believe in!!
Whether you feel the need to label yourself as Christian, atheist or agnostic is up to you, but I wouldn�t lay awake at night dwelling on it. As said above, just live.