I think I would describe myself as someone who is absolutely convinced there is a deity. Although, I think I would say those words meaning "I have been fully persuaded", but you might hear those words and understand me to say "I have infallible knowledge".
Hey, whatever fantasy you're into is your own bag. For me, I need strong evidence to start developing a belief in such a nebulous idea as a deity, and I am so amused when people tell me that it is a certainty.