One thing they do is take the texts about "these things" happening before "this generation" passes away as referring to everything--the 2nd coming and Last Judgment included. So they insist that these things had to have happened before the current generation who heard those words was gone. Whereas most Christians understand those things related to the Second Temple, or the mistreatment of the early Christians by Jewish authorities, and even viewing the Son of Man coming into His kingdom as referring to the Transfiguration/Ascension rather than the Parousia. Essentially everything gets condensed into the stuff about the Second Temple.
The worst, I'd argue, is actually how Full Preterism deals with Christian hope. Full Preterism denies the future resurrection of the body, the future renewal of creation, and instead argues that resurrection just means the soul going to heaven, and new heavens and new earth have nothing to do with the material creation. There is no Eschaton, no conclusion, no resolution outside of the subjective and personalized eschatology of going to heaven or going to hell--things down here on earth will just continue like this forever until the eventual heat death of the universe (presumably). There is no definitive conclusion to the problem of evil, there is no finality to the problem of death, injustice continues down here and the only address to justice and injustice is personal judgment at death.
There's a reason why Full Preterism is considered heretical by the majority of mainstream Christianity.
-CryptoLutheran
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