Step two:"do you now believe or are you even willing to believe in a power greater than yourself?". Belief is not actually required at this stage and a good thing too.
I didn't believe when I took step three, but I was willing to believe. AA's solution to alcoholism is a spiritual experience leading to a working relationship with a higher power that will,provide a permanent defence against the fatal first drink.
The purpose of steps three and onwards is to bring this relationship to life. I didn't begin to feel the presence of my creator until after step five. Have a read of the fifth step promises, page 75 I think. Of course the ninth step promises are another example that belief develops as we grow through the steps.
Some folks, perhaps many, have their religious convictions right from the start. The rest of us grow into our own understanding through working the steps.