The ironic job acceptance
Abilene is abandoned by her father, but not because he hates her. Quite the opposite. He is going to accept a very arduous job to provide for her from afar, but she needs a place to stay. She lives with a local clergy and begins her young independent life without her father's guidance. She is alone without him, but she is somewhat taken care of, so she gets to explore her identity while he's away.
The ironic identity of the father
The girl learns that her father is a wily, rascally kind of guy with a propensity to break the rules. He was kind of a loner, tending not to be closely woven into communities. This is ironic because that means that Abilene herself might have inherited those qualities from him. She is also fiercely independent and fearless, and she's not afraid to bend the rules. She is like her father, she inevitably learns (through dramatic irony).
The irony of religion and horror
In this book, the church is a haunting threat on Abilene's imagination. She learns about the horrifying Rattler, a nun who shakes her rosary angrily from the woods, which is indeed horrifying. The irony of the symbols is a reminder that alongside promises and helpful ideas, religion is also dangerous in some cases, and it can be used to make people feel fear, which is ironic given religion's supposed role to give hope.
The irony of the miner's story
So these folks were contractors who worked in a small town at a mine, hired by a powerful local who died, giving the diviner's family a chance to possess the land and business and start lives in the community as permanent parts of it. Instead, they are stopped at the finish line by conspiring church folks and the undertaker. The irony is that religious folks were xenophobic about inviting new members to their community.
The ironic letter
While trying to find the truth, Abilene is threatened by an anonymous letter that tells her to discontinue her curious quest for truth. Instead, she pushes further, eventually deducing who it was that sent the letter. She is ironically antagonized for doing nothing wrong, because she is close to discovering something unsavory about Manifest, Kansas.
