What is your understanding of the following passage? There are several issues to be found there to be sure. So, what are they? and what do they mean?

Matthew 7:21-23 (ASV) "21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father who is in heaven. 22 Many will say to me in that day, Lord, Lord, did we not prophesy by thy name, and by thy name cast out demons, and by thy name do many mighty works? 23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity."