Warning: Contains spoilers for Immortal X-Men #1
There is a long-held theory among Marvel fans that, in the narrative universe of the House of Ideas, Jesus is considered a mutant. It seems that, despite how controversial it is, this idea is still present as Marvel resurrects it once again in Immortal X-Men #1, by Kieron Gillen, Lucas Werneck, and David Curiel.
Jesus is actually a half-canon character in Marvel Comics. Most famously, he appeared in some stories featuring the character Howard the Duck, but was also mentioned as a real historic figure by other, more reliable, Marvel characters, such as the Sphinx. The theory that he was in fact a mutant was officially addressed for the first time in House of M #2 by Brian Michael Bendis and Esad Ribic. In that alternate universe where mutants are the dominating species, Kitty Pride is a teacher and she asks her class who the first mutant was, specifying that Jesus and Moses do not count as they were not "official." Besides these passing references, no official statement has been made on the matter in Marvel stories, understandably so, but it seems that the comics' creators are still not willing to let this theory go.
Marvel's mutants actually already have their own Messiah: Hope Summers. As the first mutant born after the M-Day, when the Scarlet Witch de-powered 90 percent of the mutant species, Hope was seen as a savior. Years later, her own mutant ability of power manipulation, augmented by the Phoenix Force and by a repentant Scarlet Witch, undid the "Decimation" and brought back the mutant species from extinction. Hope is also one of the Five, a group of mutants who combine their abilities to create the Resurrection Protocols, a process that makes the citizen of Krakoa essentially immortal. Considering all this, it is obvious that some mutants see Hope as a religious figure, and none more than Exodus, a religious zealot who was a Crusader in the 12th century and specifically mentions that Jesus was in fact a mutant.
When Exodus goes to recruit Hope to join the Quiet Council of Krakoa, he cannot hide his reverence for her as a religious figure. He calls Hope "Messiah," and references her being chosen as a host by the Phoenix as "The Holy Spirit came upon you." He believes that Hope's work with the Five has given mutants an actual Heaven, the Waiting Room, a pocket dimension created by the Scarlet Witch that exists in a liminal space between life and death. The Waiting Room allows Cerebro to scan across time and space for every mutant who died before Cerebro started its backups or before their X-gene could manifest. The most outrageous of Exodus' declarations, however, is that "the Nazarene Mutant inspired a religion among humans by raising a couple from the dead." That is a clear statement that Jesus was a mutant, or at least that is what Exodus believes.
Exodus' interaction with Hope is interesting because the girl can, in fact, be considered the savior and Messiah of the mutants, and regardless of how she feels about it, this will always have religious connotations. However, the reference to "the Nazarene Mutant" seems just a gratuitous way to stir controversy. Exodus implying in Immortal X-Men #1 that Jesus was just a misunderstood mutant - just like it was done back in House of M - has just too many dangerous connotations that Marvel certainly does not want to face, so it's pretty likely that this will remain a passing reference with no consequences in future X-Men stories.