There are some things religious Pagans are not encouraged to talk about. Doubt is one of them. I believe that the Gods exist, that They are real entities, who rule over life and death, and who dictate the way we should behave through teachings found in mythology and ancient societies. I chose to follow the Hellenic Gods in Their teachings, not disregarding that there are other Gods, but recognizing my human shortcomings, I could never honor all of the Gods in the way They feel They are entitled to be worshipped. And so I leave the worship of the Norse Gods to the Asatruar, the worship of the Egyptian Gods to the Kemetics, etc. I have specialized, so to say, in the Hellenic Gods, but to me, all the Gods are real and worthy of respect.
I didn't grow up religious. My parents were raised in various denominations of Christianity, but they had both rejected it before I was even born. My parents do not disapprove of faith, but they discouraged it, regardless. I did not have an easy childhood, and by the time I was twelve, I was already searching for religion, longing to satisfy the need in myself I found to reach out to beings beyond my reach who could offer me something to hold on to. I investigated the common, major, religions and found them lacking. I can see the beauty in many of them now, but for my twelve year old self, they were passive and lacking in what I needed: structure, active Gods, and the focus on household worship.
I found Paganism and self-dedicated after a year and a day of reading and practicing. I was thirteen at the time, and while I did not believe in the God and Goddess I found int eh books, the concept drew me in enough to start performing the rites, to start celebreating the festivals and to find my peace there. It took me years until I truly believed in the Gods, at least four or five years of active practice. It wasn't something that happened overnight, but I did find myself looking back and thinking 'when did I start believing?'. For me, it wasn't a specific ritual, or a moment in time that cemented my faith. Once day, I realized that I believed, and that was that.