The marks of false Christians are many. First, they will allow you to become a member of their group but they put great group pressure on you should you want to leave. Second, their leader or leadership thinks for the group and fears the people thinking and having thoughts of their own. Third, they have strong leadership centered on one person. They may often dictate how you should dress and what you are to do. They may even ask you to give them financial control of your income. Fourth, the leader will have special revelations or insights. At times these revelations may legitimizes their behavior, which others might think to be wrong. Fifth, the group will often have control of all information or literature to control what people know. Sixth, the group will often have their own translation of the sacred books, which they interpret for the people. Seventh, the group often has another set of books which they rely on more than the sacred books, for these other books have the details of their practices.
Often true Christians call these false Christians cults. They will have many elements of the following: A new truth that hasn’t been revealed before and supersedes and contradicts all previous revelations; New interpretations of the Bible that they alone hold to; A non-Biblical source of authority which is usually revealed exclusively to its founder; Another Jesus then the one found in the Bible, usually rejecting Jesus’ divine nature; Rejection of Orthodox Christianity; Double-talk (saying one thing publicly but internally believing something totally different); A non-biblical teaching on the Nature of God concerning the Trinity; Changing theology when things are proven wrong; A strong leadership that exercises enormous influence over the group; and false prophecy that don’t come to pass as told in the beginning.
We can’t name all the groups but the most visible ones who will probably come to your door are the Jehovah Witnesses and Mormons. The Jehovah Witnesses have their own translation of the Bible, which supports their belief. Their Bible does not follow the original languages of the Bible from which it was written. The Mormons have another book they say came after the Bible which is the latest revelation of the last prophet-Joseph Smith. They believe an angel came to Joseph Smith with a revelation of a book, the book of Mormon. Mormons look to the book of Mormon more than the Bible since it is the latest revelation. These two groups are aggressive and go door-to-door in the community selling their books and wanting to talk to people.