Is religious "preaching" rooted in narcissism?

I think there's more to it than narcissism. Human beings are generally social creatures who like to form groups. And beliefs are a strong bonding mechanism for groups.

I think believers preach for lots of different reasons, but I think there may be a very basic need in people to try to spread virtually any of their own beliefs or behaviors or knowledge in order to try to bond with others.

So if I had to guess at the "root" of the behavior, I would say it's probably a cultural bonding mechanism, and may even have been a selection effect in our evolution. But I don't think it's limited to religion, I think it's more of a general behavior of which religion just happens to fit.

I think that some preachers (probably it would usually be the self-appointed types) are motivated by vanity. Having a congregation shouting "Amen!" has got to be heady stuff. But, i think that Roswell's speculation is closer to the mark for most preachers--and a point well taken is that it's not just religion which breeds preachers. Political ideology works just as well.

The putative Jesus of scripture does not say that religion is a personal matter. He does emphasize a personal involvement . . .

Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you.

(Luke Chapter 17, verse 21, in the King James version)

But the scripture also has the putative Jesus upholding orthodoxy as embodied in the law (which for Jews, is found in the Pentateuch) . . .

For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.

(Matthew Chapter 5, verse 18)

This creates serious problems for the modern christian because it means that their boy Jesus upholds all the nastiness of Leviticus. It also creates serious contradictions between his words and his actions, such as when he successfully interferes in the stoning of a woman for adultery.

Not that I'm a big expert on the bible or anything, but I think I remember some passage about "going into your closet to pray" or something like that.

I believe the idea behind that was that prayer in private must necessarily be something personal and sincere. But prayer in public (or preaching) could easily be just an act of personal aggrandizement or for personal gain in some way (thus corrupting the sincerity of prayer).

I realize that praying is not necessarily preaching, but I think they can overlap a bit depending on the motivation.