savagewind,
Here is a point that should be taken into account, when contemplating Jesus' teaching. Jesus was not always sweet and nice to his hearers. Jesus could read people, and when he had tried to teach them several times, he knew that his teaching was not getting through to them, so sometimes he said things that shocked his hearers.
When Jesus said the things he said at Matthew 7:21-23, Jesus was telling them that they were not acceptable to him or his Father.
Jesus also said some shocking things, recorded at John 8, where he said their father was The Devil, John 8:43-45. Also at Matthew 23 where he kept calling his listeners hypocrites, blind guides, and fools. At verse 23:33 Jesus really shook them when he said; you serpents, offspring of vipers, how can you escape the judgement of Gehenna? They understood that Gehenna meant Everlasting death!
Jesus knew when to use shocking speech, we do not, because we cannot read our listeners as Jesus could.
What Jesus said worked, because many of the leaders of the Jews became believers later on, Acts 6:7.
