The Bible says that on the judgment day it will be revealed that some who think they are Christians are really not. In the Sermon on the Mount, in Matthew 7:21-23, Jesus said,

“Not everyone who says to Me, ‘Lord, Lord,’ will enter the kingdom of heaven; but he who does the will of My Father who is in heaven. 22 “Many will say to Me on that day, ‘Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many miracles?’ 23 “And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness.’

This may seem to you to be a very strange thing, that some people will be so self-deceived, that they think they are Christians when they are not. How can this…