The thread said they are called "not Christians" for things they don't do. It's seems people are more disqualified by things they do do.
Good post! Spot on. Let me explain this a bit. A true Christian will never contradict the clear teachings of the Bible. The basic but sacred doctrines and beliefs, taught in the Bible, are what makes Christianity unique. If some fella or group decides they are Christians but start adding more doctrines to their beliefs that go against the Bible then, clearly, they can't be Christian- they defiled that which makes Christianity, Christianity. W/o being too specific let's say a church teaches it is a Christian church. But it starts teaching as doctrine (and writing, publishing) that there are people, say, who live on other planets. The Bible teaches that life, as we know it, began on earth with Adam and Eve and life will end at the Tribulation. It also says that Jesus died on this planet 'once' for all men. So we have a problem. Either God/Jesus lied (Jesus a sinner?) or that group is lying. Jesus couldn't die on earth and once for ALL people if people live on other planets. Which group would you believe, those who teach as God's word things that contradict the Bible or the Bible? You can't believe both, certainly, and the Bible is the standard for what a Christianity is. The other group, with teachings of men, is not Christian bc it teaches aberrant theology. This is how pseudo-Christian groups are found out. Never contradict the Bible's clear teachings (Scripture).
There are test that can be applied to groups to see if they are Christians. A few are, Deut. 18:20-22, Matt. 7:13-23, Matt. 24, 1John 4:1. Now, I'm not attacking any group. I am only saying how to know if a group is a Christian group or not. There are rules and requirement s for being a Christian- or anything else. Welders don't plumb houses, Electricians do not weld metals together, and those who go against Christian values, doctrines and beliefs are not Christians.