These aren't the type of beliefs I'm really referring to.  However, for argument's sake - You are proving my point by having gone from a belief in God to not believing.  Now you say you couldn't go back.  I agree.  Unless, you had some extremely compelling motivation. 

Examples:

You have an encounter with God - obviously you'd instantly believe.

You're an alcoholic so you goto AA and they tell you flat out - Believe in God or die drunk.  Anyone sober in AA has CHOSEN to believe in God (of their own understanding) and many, in fact, a great many are agnostic or atheists when they first went.

You had a spiritual experience you couldn't explain any other way then by God.

New evidence came to light that irrefutably proved the existance of God, and then you might grudgingly accept it once it become commonly accepted as undenyable fact.

You are about to die and you don't want to think this is the end, so you choose to believe at the 11th hour (and 59th minute) in hopes of being 'saved'. - This happens a lot.

3 of those are external forces creating a change, two are internal decisions to change your belief, the last one commonly done on the very whim fkusumot was asking about.

Such drastic changes in ones perception of reality are referred to as epiphanies. You have little to no control over such occurrences. You cannot deny a sudden revelation. They are permanent alterations to ones mental landscape, and effect all other facets of your beliefs. They most often require the reworking or discarding of old beliefs.

The question isn't can you change your beliefs, but how can you not change your beliefs. The effort to prevent changing your beliefs is in fact the fervent belief that one has the power to change their beliefs, or the belief that you can force yourself to believe something.

Change is at the core of what it is to be human. We never stagnate we are constantly in flux, and even our oldest beliefs can and do fall out of favor with our reworking as much as new ones take their place. As long as you can maintain a cognizant thought your beliefs can be changed.

You absolutely can change your beliefs. All that is required is the belief that you can. Beyond that you have no choice in the matter your beliefs will change until you reach that specific outcome. This is a inherent property of consciousness. This is the same conundrum raised by the question do you have a soul. The ability to ask or conceive of the question is the proof that you do possess one.

http://en.wikipedia.org/wiki/Free_will

^ i choose to not click there but isted do this..........

 Nope.

I'm not even an atheist... but if god came out of nowhere and started talking to me i'd expect he was some sort of hallucination/alien/guy from the future/dream etc.

The number of people who answered the questions "Can you change your habits?" or "Do people have free will?" rather than the question asked makes me die a little inside.

 I think I'd be more likely to believe it was god than a guy from the future.  Time travelling paradoxes would do more destroy my worldview than many incarnations of a supreme being.

The question of free will is directly related to whether or not you can choose your beliefs.

What if he was a cat?