charlieb -
It sounds like you may be talking about some of the fundamentalist Christians who do seem to think they must convert every person they meet. But the interesting thing about some of these groups is that they all seem to think their particular brand of Christianity is the only correct one.
Early on in this thread "Reason" made the following statement:
"A good Christian missionary does not impose God on anybody. Belief in God is a choice."
I agree with this point. As a Christian I am happy to discuss my religion with anyone who is interested, but I do not feel it is my 'duty' to go out and impose my beliefs on others (Note that the word 'impose' implies "force"). As in "Reason's" point, belief in God is a choice and I believe each person must make that choice for himself. For me to assume that EVERYONE must be Christian would be to assume that any other way to worship God is wrong or incorrect. I'm not sure that is for me to decide.