These two verses are speaking of people who are under the belief that they are in a righteous relationship with Christ and are living to the best of their abilities through Him. Some will prophesy, some will cast out devils and others will believe they are doing the will of the Father because of their works. They are convinced that they are in good standing with Christ. What of their salvation? What of their rebirth? Christ will reject them because he never knew them. They are lawless and lack intimacy with God.
I'm probably going to get the stuffing beat out of me for saying this...
But I agree...this passage is pretty alarming. There are people right now living their life thinking they are going to make it and will not. Now that is pretty scary to me.
Another thing that concerns me with this passage... is how on earth is an "unsaved" person going to do those works mentioned.
I mean, how could an unsaved person cast out devils and prophesy. To truly do those types of work it would take the spirit of God and Jesus didn't say that they were false prophets or falsely casting out devils.
Matthew 12
25 And Jesus knew their thoughts, and said unto them, Every kingdom divided against itself is brought to desolation; and every city or house divided against itself shall not stand:
26 And if Satan cast out Satan, he is divided against himself; how shall then his kingdom stand?