On the one hand, I can appreciate this, for I experienced it. A camp I attended in 7th grade had a preacher whose whole sermon consisted of, 'Do you know that you know that you know that you know that you know you are saved?' It put great doubt in my heart, and led me to a private meeting with God some months later. To this day I do not know whether I was saved before then, as a child, or right then, as a young teen.
...but having said that, aren't preachers supposed to call on people to examine themselves?
2Co 13:5 Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?
In my experience, although impressionable children can be easily confused or manipulated, the average adult sitting in the pews at church is a little too convinced of the certainty of his own profession for my taste. So many lead a life that shows no sign of an appetite for God, and the things of God, a life that is filled with the world, and lived in pursuit of vanity - and yet they blithely sit there quite secure in their own mind of their eventual spiritual destination.
Mt 7:21 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 which is in heaven.
22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.
I do not want to confuse people. I do not want to lead people to doubt, but rather to faith. I do not want to manipulate people for my own ego, or my ministry's reputation. I do not want to teach, or even imply, a works based salvation....but I do want people to examine themselves, whether they are in the faith. I think a bit more of that would be a healthy medicinal dose for the average Sunday morning glory in the average church in this materialistic, narcissistic, worldly Vanity Fair we live in.