BSM1 makes a good point. Your little girl loves you and knows you love her, so you really don't need to get stressed about this. If you stay calm and unaffected, it won't become an emotionally charged issue for either of you.
She probably doesn't actually believe in god anyway , she is being affected by her peer-group probably, and they are just repeating what their parents said. Dismiss it in a good-natured way, and don't cast aspersions on the people who do believe, that just ups the ante on conflict and may make her feel stressed about how you feel about her friends.
You could also use what is called 'upaya' by hindus and buddhists - it means a helpful trick, usually translated as 'skillful means' - something like "some people don't understand that god really means love. And you know we love each other very much, and we love (...name the ones you love, including the dog and cat). But that's OK, one day they will understand."
But don't buy into any stress about it. If she expresses fear that you will go to hell, your calmness and simple rejection of the notion is all you need to communicate, exactly as BSM1 said. And give her a big squishy hug. That trumps any BS. Your unqualified love and acceptance matters more to her than anything else.
Mostly, just be honest. Kids can tell when adults are being honest, and they do respect it.