A (negates what follows)
Theism (belief in the existence of God )
Thus, it's a belief that God does not exist. The Jesus aspect is a red herring of sorts.
Theism is a rather large umbrella of spiritual, religious beliefs. Under that umbrella there exist many variations, including Christianity, Deism, Judaism, Islam, Greek Mythology, etc. They all share a common thread. They all believe in the existence of one or more Gods. The common thread they don't share is Jesus.
As an example: Founding fathers Jefferson , Franklin, and likely others, believed in the existence of God but not in the existence of a supernatural Jesus or supernatural powers and events. They were Deists, a subset of Theism. They believed in the possible existence of God but not in the supernatural aspects involved with Christianity.