Do one better, tell them that your sky daddy is bigger than theirs and could beat him in a fight, then pull out pamphlets on your chosen fake god and give them to them for a change.
Literally did it last week, couple Mormons came to sell me bullshit, I pulled out a couple pamphlets from The Church of the SubGenius and told them the good word of "Bob". Much more fun, and it's harder for them to dismiss than anti-theism outright because they're used to that but like nobody does this lmao.
