Here is an attempt for an in-game answer.
Within the D&D game, the closest in-game concept that closely mirrors your description is the philosophical position of the planar faction known as the "Athar". The in-game word for members of this philosophical club is Defier. The term originated during the 1990s (AD&D 2e) with the Planescape campaign setting. The faction was also updated to D&D 3/3.5e in articles published in the Dragon magazine.
Once a character travels to the Outer Planes, part of the core cosmology of the D&D game (also known as the Great Wheel Cosmology), it becomes quite clear that deities are super-powerful beings. Members of Athar accepts their presence, but sees them simply as powerful beings and not worthy of worship. Some militant defiers will actively try to undermine religious orders, while others will simply ignore them. So your character would just be such a "soft" defier.
Another in-game word that is used in the Forgotten Realms setting is Faithless. In the polytheistic Realms, everybody worships all the deities, with one, a so-called patron deity, given the most importance. If you do not worship any powers at all, you are said to be faithless.
However, please note that there are some consequences. If priests learn that your character is a defier, they are likely to refrain from using their beneficial spells on you. And on Faerun, if you die faithless, you end up as a brick in a wall in Kelemvor's realm for the rest of eternity.