Pho my friend your argument is based on the assumption that they knocked on V's door with the intent of changing his views, I believe they were in fact just reaching out as Olivia has stated, simply trying to find others in the community that share their beliefs.
It's a fact that the various church's do in fact find new congregation members like this they also find people in need of their welfare services, the real door knockers are the Mormons.
The is a million jokes on how to get rid of Mormons but the method I use is quicker and more effective than all of them, I just say "I'm sorry but we are Church of England"...............all done, all over and the funny thing is I didn't have to be rude.
Ken