No True Scotsman is a crappy fallacy people knowing nothing of church history
Actually, it's not a "crappy fallacy." It's a legitimate one. You're twisting the word Christian the wrong way here.
First off, Christian basically means any religion that believes in Christ as the son of God (Abrahamic). This could mean Roman Catholic, Protestant, Mormon, Baptist, and I'm sure many more. They are all still Christians. If you think of it this way, dissent means nothing. Many people can "dissent" all they want, but if they aren't separating the label they use to describe themselves, they can still be committing the fallacy of No True Scotsman.
Take for example the following scenario:
Person A is eccentric and extremist in his opinions on religion. He takes the bible as literal fact and believes that Christ is his saviour and that gays are evil and sex before marriage deserves to have you stoned on the city wall.
Person B is tolerant, thinks that while Christ is his saviour, that we should still love everybody and that most of the bible consists of old traditions that aren't in line with proper human values because it was formed by a culture that existed long before much of our current knowledge.
The requisite to being a Christian is accepting Christ as the Son of God (in this case, we'll say Christ as a saviour of our sins, or a messiah is equivalent to that). Both persons are therefore Christian. If either Person A or Person B accuse the other of not being true Christians because they don't share the same opinions on all topics that their religion or system of beliefs stems from, then they are committing a fallacy where they are changing the definition of the predicate being a Christian to suit their personal opinion. That is the No True Scotsman fallacy. It's got nothing to do with history, it's everything to do with logic and the meaning of a term.
But religious people I know feed the hungry, house the homeless, and give a caring ear to people locked away in prison who need someone stable and normal to talk to. And part of that is because of their religion. Not because they feel obligated to do these things to earn God Points, to be redeemed for quality of housing in the afterlife. But because they believe that it's the right thing to do -- that they are merely passing on the love they recieve from their creator to those around them who really need it.
Part of it may be due to religion, however, I feel that this is simply confusing correlation with causation. From the very beginning humans knew that they needed the strength of a community to survive. Helping out your community (religious or otherwise) has long been the "right thing to do." They don't need to pass on any love of any creator for this to be possible. Our current survival is proof enough to show that humans use communities and cultures to survive, and that taking care of your neighbour means that he/she will eventually take care of you (in the broadest sense, some neighbours are dicks). This is the very concept behind social safety nets.
But if you're claiming "99% of religious people are insane" it would suggest that maybe you are not thinking of those people as human beings, merely wrong-thinking automatons.
An automaton can't even be insane by definition, since insanity is defined as being in a state of mind that prevents normal perception, behavior, or social interaction; seriously mentally ill. If they were automatons, they would always be in normal perception or behaviour relative to their default state. However, if we go under the assumption that people who believe in deities are in a state of mind where they cannot perceive things normally (or objectively, aka as things are), then "99% of religious people are insane" is a true statement. I don't personally believe that 99% of religious people are actually insane, but history tends to show that religion has been more or less used as an authoritarian device to control or direct people. So while I can't say that religion makes everyone insane, or evil-oriented automatons, I can say that there is a vast majority of religion that is used to control and subjugate other humans. And quite frankly, that's exactly the kind of thing only a human could do.