Strictly speaking, heresy is the denial of one or more tenets of a faith one professes to accept; thus, Christians who disagree on major issues hurl charges of heresy in both (or many or all) directions. But Deists don't claim to be Christian, so they can't be Christian heretics.
Belloc (and Chesterton following him, I think) did call Islam "merely the greatest of the Christian heresies" but that's sort of loose usage: I guess historically there's some evidence that Mohammed got the basics of Islam from renegade Christians, but he himself -- and still less his followers -- never professed Christianity.
So Christianity is a jewish heresy but Deism is only blasphemy?
1: a dissenter from established religious dogma; especially : a baptized member of the Roman Catholic Church who disavows a revealed truth
2: one who dissents from an accepted belief or doctrine : nonconformist
Apparently Deism is only blasphemy to Catholics, but is a heresy to others denominations according to Mirriam-Webster.