There is a very easy way to tell the difference between true and false Christians, and that is to see if their lives match what is written in the scriptures. False Christians in the modern world spend all of their time trying to avoid suffering. They refuse to be uncomfortable, they want to completely blend in with the lost world, and they will not take stands for absolute truth. False Christians are also known for continually trying to justify living in sin.
Real Christians on the other hand, have family members turn against them. Lost people hate them, and sometimes will even threaten them with physical violence. Real Christians study the Bible, and take firm stands on doctrine.