They mean it from the goodness of their heart. But they just can't take no for an answer.
Sadly, I must admit edgar, that you are right. There are far to many Bible-Toting Christians out in the world that want to lay seige to every person they think is not going to church on a regular basis (Even I hide from the long-skirt wearing jehovah witnesses & other church folk when I see them trotting down my street w/ their pamphlets and stuff - I do not answer the door).
Personally, my faith is mine, and while I do share it with others who do not believe, I ususally do so when it comes in in topic, or if it has something to do with present conversation. Some people (a lot of people) don't think I do as much as I should to bear witness to people, but I just do a more subtle thing and I don't go around with "Thus saith the Lord" hanging out of my mouth. I won't lie, the Bible tells us to win souls for the Lord, and while I've never actually 'led' anyone to Christ, when I do mass invitations to concerts and fairs and plays that my church puts on, it's in the hope that that will happen if and when they come.
I know a lot of Christians that are not nearly as easy going about it as I am, and that plays a big part in making the world at large think of us as trying to charismatically (or not so much that) get everyone over to this side...
You guys & gals never sway my faith, but once again, it's always interesting for me to think on the things that are said in these threads.