Is there anything one can do to be excluded from Christianity? Not including the unpardonable sin or changing religions.
Throughout the years, Christians have done some pretty awful things, some in the name of Christianity, some for other reasons; The Crusades, The Spanish Inquisition, The genocide of Native Americans, Slavery, bombing Nagasaki and Hiroshima, the wars in Vietnam, Iraq, Afghanistan, the terrorist attack in Norway, and continued hostility towards homosexuals, Atheists and people of other faiths, particularly Muslims.
But when the more liberal Christians denounce these acts, they often say that the perpetrators are 'not true Christians'. I'm aware that there's very little in the teachings of Christ to justify genocide. But such acts are found in the Old Testament at the command of God.
Even if such acts were only justifiable in those circumstances because God commanded it, everyday Christians do many things every day that are not Biblically sanctioned. If an unrepentant murderer is not a true Christian, is an unrepentant homosexual also not a Christian? What about an unrepentant liar? Or a guy who disrespected his parents once 20 years ago and hasn't got around to repenting for it yet? As far as I know, the Bible doesn't differentiate between sins.
The logical conclusion of this is that since every different sect of Christianity has slightly different rules, every one of the 100s of sects of Christianity are wrong except perhaps one, and therefore the adherents are not true Christians. Even the believers in the correct version of Christianity will be imperfect in their religion in some way, except for maybe 1% of the adherents who are absolute boy scouts. This means that only a tiny percentage of a group of people, who themselves only make up a tiny percentage of the Christian population, who account for less than a third of the world, are not true Christians, are not saved. God's ultimate mission to redeem mankind through the sacrifice of Jesus succeeded in saving about 17 people of the billions who ever lived.
This would make Jesus a failure, in my book.
But on the other hand, if Christians are perfectly capable of committing some of the most horrific acts in human history, then being a Christian doesn't make you a better person than an Atheist or the Jews of the OT who did perfectly fine without him, so again, the ministry of Christ, the prophets, missionaries, writers and preservers of the Bible are all meaningless; they don't make you a better person.