I know it's a sales pitch, it's just so unfortunate that the sale's people don't see it that way. 
It's ok. I'm not going to tell people how to spend their Sundays, or money.   But I do have a few words for those who have suggestions about how I spend mine.
When he came to my door just then, here's what I told him;
I'm a passive agnostic.  (This interested him, so I explained).
It means I'm ok with not knowing.  I don't know whether the universe (or universes) were created by a conscious being, so I can't begin to fathom how that being expects me to behave.  I would however like to think that if there is a God, and this life and Earth is a gift, that he would be ok if I didn't choose a church to go to, as long as I a) enjoy it b) take care of it.  It's how I hope people treat the gifts I bestow upon them. What I get out of doing good is a warm feeling in my heart - I don't need recognition to feel this way.  
I went on to explain that although I do not have definitive proof either way, that such proof would not have an effect on how I live life.   This is why I have never pursued an answer, not that I would ever feel completely satisfied with any conclusion I come to.  
He went on to ask me how I felt about the way the world was.  I raised my eyebrows, not exactly sure what he was getting at.   There's a lot wrong with our kind, I blame most on greed, but have seen what religion has done to people throughout history.  I didn't explain this to him - I knew it would be a fruitless attempt.  Had his child not been standing there in his cute little suit, and uninterested look on his face, I would have elaborated on my response, but instead I avoided giving him my opinion on this.  Maybe he wanted to tell me that God was angry, but he probably knew I wouldn't buy it, so he didn't go there.
He told me that if I were to ever seek an answer, that I was more than invited to go to a seminar. He thanked me for the chat, explaining that he doesn't run into many agnostics.  Him and his bored to death son got back in their car, off to the next good deed.  Left me wondering what he and his little boy thought of me.  How would he explain what I said to his son?  Did Satan lead me astray?  Am I too stupid to figure it out? Are my parents to blame for my lack of Bible education?  Will I be saved one day, or because I didn't comply, am I doomed to damnation?  Will they say a prayer for me tonight?
I can only hope that kid hates dressing up enough to grow and look for his own answers.  I hope that the fear of unearthly consequence will not deter him from questioning what he has been taught. I hope, but I won't take credit for it if he does.