That's quite a leap.
I've never been much of a "joiner" because it is rare that I sufficiently identify with any given group's beliefs and goals that I felt comfortable being a member.
But what I do believe is much closer to "Objectivism" than to "Marxism" such that I find your statement rather troubling. Objectivism may "reject" Christianity, but I don't recall reading anything that suggested that Christians should be sent to penal institutions or death camps by Objectivists. My reading of Objectivism is that objectivists just want to be left alone by Christians.
I also am not aware of any analogy in Objectivism of Islam's mission to kill the infidels.
I don't claim to be an expert, but isn't it even a stretch to refer to "Christianity" as though it is one thing and not many things some of which are contradictory?
This site is run by an Objectivist: Christianity Is Evil.