The evidence may be found in a scene from one of the extended versions where Maximus witnesses Christians being thrown to the lions. "Gladiator" is based during a historical period where Christianity was starting to filter into the mainstream with devastating results. Although the movie is void of any Christian reference in the plot, you can infer from the rowdiness of the crowds, "the mob" of Rome, that there was turmoil within the psyche of the population and that changes were taking place. These were times of desensitisation; there was death, disease, hunger, violence, and the emperor needed this in order to surface as the savior, or at least as the supreme leader in which everyone would place their hopes. This is why Commodus seems so pleased to offer "the mob" the bloodshed spectacles at the Colosseum, and to provide them with bread and wine in actions designed to promote himself more than help the people.
A hint of spirituality is also evident in that Maximus dreams of an "afterlife" with his wife and son. Although the idea of life after death is older than Christianity, it is a point to ponder on considering the very earthly, rogue, and gritty nature of the movie and its characters. The movie's beginning scene, called "the hand over the wheat", also depicts a form of heaven. Again, the concept of going to a heaven or a Hades is older than Christianity, but it denotes that Maximus does possess the Roman Virtue of "Auctoritas" which deals with the self, self-realization, transcending, and having spiritual authority by serving as a moral model to others.