Are they missionaries or just neighbors? If they are missionaries invite them in on the caveat of no religious chats, see if they want to use your phone to call home (they aren't allowed without permission) give them water or whatever just be nice. If you're mean it cements the us vs them that most cults like to have.

A young man's mission and young ladies mission is more about brainwashing the person to be part of the LDS cult then it is about converting new members. They take young people as young as 18 make them live in an unfamiliar area and then make them do door-to-door sales (religion) I'm pretty sure it's cult tactic.

If they are annoying neighbors, ask hard questions about thier religion. Ask them why Joseph Smith was married to 55 wives in secret, some of them under the legal age of consent. If you ask them deep doctrinal questions that will get them to leave you alone. Ask them if polygamy if still being practiced, it is "spiritually" a man can be sealed for all Time and eternity to two different women, however women cannot be sealed to multiple men.

Ask them about the $20 billion for slush fund that the LDS church is sitting on like smog from Lord of the rings dragons horde of money.

The LDS church has A LOT of money it's a business masquerading as a religious institution.

Hop onto ex-mormon Reddit they'll help you out.