Would someone please explain to me what evidence there is for the existence of a god or deity?
Depends what philosophical position you take though (without getting extremely technical), it depends what you mean by evidence.
For instance, there are very good arguments that show an all loving, all knowing God might not exist but if he does exist, it suddenly doesn't make him disappear. Conversely, if you think you have very good proof for God, it doesn't suddenly make him pop into existence if he doesn't exist.
That said, such arguments are only of limited value. Personally, i believe we can't actually choose to believe in something like religion, as in, wake up one day and suddenly i decide to become a methodist. The argument ive made around this is very long and fairly complicated but i'll just say that so people know where i'm coming from.
That said, i'm sure it doesn't surprise anyone here there isn't any fully conclusive and widely accepted argument for or against a God. It's easy for one side to play "Dr.No" just like tony abbot and trash the othersides argument but when they present their arguments to the contrary, most of them are just as open to being trashed. Both these reasons are why arguments of that nature often turn into huge circlejerks, its not like your argument will convince many, if any to change teams so to speak. It usually takes something more than that. Most of the time its just people throwing words at each other, telling the other person why they're wrong and why they don't believe what they just said, rinse and repeat.
If you're just looking to refute every single argument that comes your way, you won't find much proof in anything really. We can't under estimate the effect of psychology in things like this either.
The cosmological argument is a good place to start, especially so because you can't really prove either way -
http://kingpomba.tumblr.com/post/10354513929/marios-dream-turtles-all-the-way-down-argument-forAlvin plantinga's notion of "properly basic" is also another place to go to.