Diluting God's wrath is not heretical?
This is the book which says, "blessed are those who read the prophecy of this book and those who hear it and take it to heart."
And
"I warn everyone who hears the words of the prophecy of this scroll: If anyone adds anything to them, God will add to that person the plagues described in this scroll. And if anyone takes words away from this scroll of prophecy, God will take away from that person any share in the tree of life and in the Holy City, which are described in this scroll."
As an example, I would also remind you about what Paul said regarding Hymeneus and Philetus who were teaching that the resurrection had already taken place. He said that it was godless chatter and that this teaching would spread like gangrene and that they had wandered away from the truth, as well destroying the faith of some.
Full Preterism teaches that the events of Matthew 24 and Revelation has already been fulfilled, including the resurrection. That would immediately put them in the Hymeneus and Philetus group, which means that what preterists teach is godless chatter, will spread like gangrene (and has) and that they have wandered from the truth.